It has been investigated that the role of donor such as tributyl phosphate (TBP) and ethyl benzoate (EB) in preparing of NdCl3 supported catalyst for olefins polymerization. The surface complexes were produced when the NdCU reacted with TBP and EB. There is a TiCl4/ TBP complex occurred in NdCl3/TBP/TiCl4 catalyst

whereas only the complex of EB with NdCl3 was discovered in NdCl3/EB/TiCl4 catalyst. The polymerization activity of above mentioned two kinds of catalysts for ethylene is much higher than that for propylene. The kinetic curve of polymerization for ethylene is of the decay-type with NdCl3/TBP/TiCl4 catalyst. The interaction between NdCl3 and MgCl2 supports occurred when the NdCl3 and MgCl2 were grounded together

which accelerates the breaking of supports.A higher activity of co-support NdCl3-MgCl2 catalyst for olefins polymerization was obtained.