The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11),RTiCo_(11) and RTi(Fe_(1-X)Ni_X)_(11) compounds,where R represents Nd,Sm,Gd,Tb,Dy,Ho,Er and Y.Neutrondiffraction and Mossbauer spectra analyses have been used to study the nuclear and magnetic structure ofthese compounds.the Fe,Co,Ni and Ti atoms are found to exhibit strong site preference with f and j sites fa-voring Fe,Co and Ni atoms and the i site Ti atoms.Two different types of magnetic behavior were observed inthe RTiFe_(11) and RTiCo_(11) compounds.In the former,the interatomic distance and the number of nearestneighbor atoms play essential roles.In particular,anomalous thermal expansion behavior is presented inRTiFe_(11).In the latter,the magnetic properties are essentially determined by the modification of the cobaltelectronic configuration brought about by the transfer of rare earth conduction electrons to the transition 3dband.The saturation magnetization,Curie temperature and magnetocrystalline anisotropy data of RTiFe_(11),RTiCo_(11)and YTi(Fe_(1-X)Ni_X)_(11)are presented.A tempt to improve the intrinsic magnetic properties inRTiFe_(11)has been made,and the results are reported.On the basis of the crystalline field theory by using asingle-ion model,the anisotropy constants and their temperature dependence of the R ions have been calcu-lated,which helps explain the spin reorientation observed in RTiFe_(11). The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_ (11), RTiCo_ (11) and RTi (Fe_ (1 -X) Ni_X) (11) compounds, where R represents Nd, Sm, Gd, Tb, Dy , Ho, Er and Y. Neutrondiffraction and Mossbauer spectra analyzes have been used to study the nuclear and magnetic structure of the compounds. The Fe, Co, Ni and Ti atoms are found to exhibit strong site preference with f and j sites fa-voring Fe , Co and Ni atoms and the i site Ti atoms. Two different types of magnetic behavior were observed inthe RTiFe_ (11) and RTiCo_ (11) compounds.In the former, the interatomic distance and the number of nearest neighbors atoms play play essential roles. In particular, anomalous thermal expansion behavior is presented in RTiFe (11). In the latter, the magnetic properties are essentially determined by the modification of the cobaltelectronic configuration brought about by the transfer of rare earth conduction electrons to the transition 3dband. The saturation magnetization, Curie temperatu (11) and YTi (Fe_ (1-X) Ni_X) (11) are presented. A tempt to improve the intrinsic magnetic properties in RTiFe_ (11) has been made, and the results are reported. On the basis of the crystalline field theory by using asingle-ion model, the anisotropy constants and their temperature dependence of the R ions have been calcu-lated, which helps explain the spin reorientation observed in RTiFe_ (11).