The origin of low δ18O signals in zircons from the Early Cretaceous A-type granites in east- ern China has long been disputed. It is uncertain whether the 18O-depleted features were inherited from high-temperature hydrothermal altered source rock or resulted from water-rock interaction after em- placement. In this paper, zircon oxygen isotopes in the ～130 Ma Kulongshan A-type granites in the north- ern North China Craton are analyzed. The zircons could be subdivided into 5 types based on their lumi- nescent intensity and internal structures in CL images. Their δ18O values also vary in different types and show negative correlation with U and Th contents and accompanying cumulative α-decay doses, implying that their δ18O values may have been modified to various degrees by meteoric water-rock interaction after the accumulation of radiation damage. The idea is further confirmed by oxygen isotopic equilibrium cal- culation between co-existing mineral pairs. It is inferred that only the least-influenced zircons, with slightly elevated δ18O values than normal mantle, have preserved the magmatic oxygen isotopes. In com- bination with other evidences, it is proposed that the A-type granites are lower-crustal-derived, unneces- sarily invoking a high-temperature hydrothermal altered source. The proposition is applicable to many other Cretaceous A-type granites that have similar zircon behaviors.