Research on sulfur isotopes in hydrothermal uranium deposits with acid alterations shedmuch light on the genetic aspects of hydrothermal uranium deposits.Based on the studies ofuranium deposits of different genesis,it is concluded that δ ~(34)S of sulfides in hydrothermaluranium deposits derived from residual magma is within the range of +2‰—2.6‰,appro-ximately the same as meteorite sulfur.δ ~(34)S of sulfides in polygenetic hydrothermal uranium de-posits is slightly lighter than meteorite sulfur and varies over a restricted range(6.7‰),avera-ging—10.15‰.Two intervals can be recognized with respect to sulfur isotopic compositionsin palingenetic hydrothermal uranium deposits.δ~(34)S of sulfides formed in diagenesis,autometa-morphism and hypothermal stages is similar to meteorite sulfur.On the other hand,at the stagestarting from the alteration of uranium mineralization to the formation o uranium depositsand postmineralization the average δ ~(34)S is -7.89‰,with a wider range of δ ~(34)S variation(13.7‰),which can be attributed to the enrichment of δ ~(34)S in palingenetic hydrothermalsolutions. Sulfur isotopic characteristics of uranium deposits of various replacement-filling typesas mentioned above can be summarized as follows:1.Isotopic homogeneity is maintained in the sulfur of sulfides in hydrothermal ura-nium deposits derived from residual magma,with δ~(34)S ranging from +2.0‰ to-2.6‰,approximately the same as meteorite sulfur.2.Lighter sulfur isotopic compositions are determined is sulfides from polygenetichydrothermal uranium deposits.This may be attributed to assimilation and contaminationby the ~(32)S-rich sulfur of sedimentary origin in the wall rocks.δ~(34)S fluctuates around-9.5‰,with a small isotopic variation (6.7‰).3.Two intervals can be distinctly recognized with respect to the sulfur isotopic com-positions of palingenetic hydrothermal uranium depostts.The sulfur isotopic compositions ofprimary sulfides are similar to meteorite sulfur,while sulfides formed at the time startingfrom the alteration of uranium mineralization are obviously lighter in isotopic composition.The average value of δ~(34)S is—7.89‰,with a relatively wide range of isotopic variation(13.7‰),probably due to the enrichment of ~(32)S in palingenetic hydrothermal solutions.4.Hydrothermal uranium deposits derived from residual magma and polygenetichydrothermal uranium deposits have a source of uranium mainly from U-rich residual solu-tions generated from granite magmatic differentiation as well as from U-rich granite bo-dies,out of which the bound uranium was leached by the solutions,so uranium depositsof both types are generally large in size.But the uranium in palingenetic hydrothermaluranium deposits comes mainly from the bound uranium infiltrated and leached out of U-rich grainte bodies by palingenetic thermal water,and therefore uranium deposits of thistype are generally smaller in size.5.The crystal forms of pyrite in uranium deposits seem to be related to the originof hydrothermal solutions.Pyrite takes the form of cubes in hydrothermal uranium depo-sits derived from residual magma,while it largely occurs as pentagonal dodecahedra in pa-lingenetic hydrothermal uranium deposits,and the crystal forms of pyrite in polygenetichydrothermal uranium deposits are so complicated that besides the above two crystal formsrhombic dodecahedron and octahedron,and their polymers are also found.6.Extensive occurrence of coffinite in palingenetic hydrothermal uranium depositsmakes them distinguished from other genetic types of hydrothermal uranium deposit. Research on sulfur isotopes in hydrothermal uranium deposits with acid alterations shedmuch light on the genetic aspects of hydrothermal uranium deposits. Based on the studies ofuranium deposits of different genesis, it iswhere that δ ~ (34) S of sulfides in hydrothermaluranium deposits derived from residual The magma is within the range of + 2 ‰ -2.6 ‰, appro-ximately the same as meteorite sulfur. δ ~ (34) S of sulfides in polygenetic hydrothermal uranium de-posits is slightly lighter than meteorite sulfur and varies over a restricted range ( 6.7 ‰), avera-ging-10.15 ‰ .wo intervals can be recognized with respect to sulfur isotopic compositionsin palingenetic hydrothermal uranium deposits. Δ ~ (34) S of sulfides formed in diagenesis, autometa-morphism and hypothermal stages are similar to meteorite sulfur .On the other hand, at the stagestarting from the alteration of uranium mineralization to the formation o uranium depositsand postmineralization the average δ ~ (34) S is -7.89 ‰, with with a through range of δ ~ (34) S variation (13.7 ‰), which can be attributed to the enrichment of δ ~ (34) S in palingenetic hydrothermalsolutions. Sulfur isotopic characteristics of uranium deposits of various replacement-filling typesas mentioned above can be summarized as 1.Isotopic homogeneity is maintained in the sulfur of sulfides in hydrothermal ura-nium deposits derived from residual magma, with δ ~ (34) S ranging from + 2.0 ‰ to-2.6 ‰, approximately the same as meteorite sulfur.2. Lighter sulfur isotopic compositions are determined to be sulfides from polygenetichydrothermal uranium deposits. This may be attributed to assimilation and contaminationby the ~ (32) S-rich sulfur of sedimentary origin in the wall rocks.δ ~ (34) S fluctuates around-9.5% o, with a small isotopic variation (6.7 ‰). 3.Two intervals can be distinctly recognized with respect to the sulfur isotopic com-positions of palingenetic hydrothermal uranium depostts. The sulfur isotopic compositions of prima sulfides are similar to m eteorite sulfur, while sulfidesformed at the time starting from the alteration of uranium mineralization are obviously lighter in isotopic composition. average value of δ ~ (34) S is-7.89 ‰, with a relatively wide range of isotopic variation (13.7 ‰) probably due to the enrichment of ~ (32) S in palingenetic hydrothermal solutions.4. Hydrothermal uranium deposits derived from residual magma and polygenetichydrothermal uranium deposits have a source of uranium mainly from U-rich residual solu tions generated from granite magmatic differentiation as well as from U-rich granite bo-dies, out of which the bound uranium was leached by the solutions, so uranium deposits of both types are generally large in size.But the uranium in palingenetic hydrothermaluranium deposits comes mainly from the bound uranium infiltrated and leached out of U-rich grainte bodies by palingenetic thermal water, and therefore uranium deposits of thistype are generally smaller in size.5. The crystal forms of pyrite in uranium deposits seem to be related to the origin of hydrothermal solutions. Pyrite takes the form of cubes in hydrothermal uranium depo-sits derived from residual magma, while it largely depolymers as pentagonal dodecahedra in pa-lingenetic hydrothermal uranium deposits, and the crystal forms of pyrite in polygenetichydrothermal uranium deposits are so complicated that said the above two crystal forms rhombic dodecahedron and octahedron, and their polymers are also found. 6. Extensive occurrence of coffinite in palingenetic hydrothermal uranium deposits make them distinguished from other genetic types of hydrothermal uranium deposit.