The invention relates to an olefin polymerization catalyst for the polymerization of alkene, in particular to the polymerization of propylene, or copolymerization, and a process for preparation, the invention relates to a catalytic activity component which is prepared by novel ester ether compound, and catalyst composition which contains the catalytic activity component, and a process for preparation. The catalytic activity component takes magnesium chloride to be carrier, a noevl binary ether ester compound which is showed as the general formula I is added in the process for preparation, thecatalyst composition which contains catalytic activity component not only has higher catalytic activity and hydrogen sensitivity, meanwhile can guarantee polyacrylic resin to have higher stereoregularity when the composition is used for propylene polymerization. And the integrity of the polymerisate is better.