Abstract: Bis(2,6-dimethyl Salicylaldmine)nickel complex was synthesized by 2,6-dimethylaniline aniline nickel and bis(salicylaldmine)nickel typed complex, this complex can be used as propylene oligomerization catalyst. The complex was characterristed by IR and UV. And the thermal properties of complex was tested by DSC. The catalytic performance in propylene oligomerization was compared for two complexes bis(2,6-dimethyl salicylaldmine)nickel and bis(salicylaldmine)nickel. The effect of alkyl aluminium cocatalysts and PPh3 on propylene catalytic behavior was investegated. The complex / triphenylmethane solution system was studied by UV atlas, and a possible catalytic mechanism of the formation of the active site was proposed.