Olefin polymerization catalyst belongs to the filed of a catalyst. The catalyst comprises activity-state MgCl<2>, titanium compounds, and alcohol esters electron donor compounds of general formula I, wherein, the molar ratio of the alcohol esters electron donor compounds to the MgCl<2> is 0.01 to 1. The content of Ti in the catalyst components is 1.5 wt percent to 10 wt percent; the general formula of the alcohol esters electron donor compounds is I; the invention is applied to polymerization of olefin CH2 =CHR, wherein the R is hydrogen or alkyl provided with 1 to 15 carbon atoms, in particular to the polymerization of propylene, catalyst activity is high and isotacticity of polymer obtained is high.