Abstract:Two salicylaldehyde Ni(Ⅱ) complexes was synthesized from salicylaldehyde and 1-CHO-2-Naphthenol separately,these two complexes can be used as catalyst for propylene dimerization. The complexes were characterized by IR and UV spectrum. The thermal properties of complexes were determined by DSC.The properties of complexes /triphenylphosphine solution system were investigated UV method, and then the plausible formation mechanism of catalytic active site was deduced.