This invention relates to a catalyst system which is used for alkenes polymerizing or copolymerization, it includes solid catalyst composition A that contains titanium and organic Aluminum compound B, silicoorganic compound C, in the composing process of catalyst composition A, use aldyl ester of aryl group mon-carboxylic acid and aldyl ester of fatty series or multielement carboxylic acid of aryl group for reasonable combination, among them aldyl ester of aryl group mon-carboxylic can play a role of assisting separating agent, it is useful to separate catalyst particle; Meanwhile it is used as electron donor, it also can load on the surface of catalytic agent together with compound of multielement carboxylic esters, improve the surface structure of catalytic agent, thus improve the catalyzing function of catalytic agent. This catalytic agent that is used for propylene polymerizing has high catalytic activity and anti- impurity function, particle appearance of catalytic agent is good, particles distribute narrowly, hydro-adjusting function of catalytic agent is good, it is useful for many polymerizing technology such as seriflux method, noumenon method and gas method, molecular weight distribution of polymer is narrow, particle appearance of polymer is good, fine grits is little; Its fine anti-impurity function can effectively reduce production cost.