The catalyst for olefin polymerization contains three components A, B and C. The component A is a solid catalyst containing titanium, magnesium, chlorine element and an internal electron donor, the internal electron donor consists of 1,4-diether [2,2′-dialkoxy-1,1′-biphenyl, 2,2′-dialkoxy-1,1′-binaphthalene, 10,10′-dialkoxy-9,9-biphenanthrene] and organic acid ester or 1,3-diether [9,9-bis(methoxymethyl)fluorine, 2,2-dialky 1-1,3-dimethoxypropane]; the component B is an organoaluminum compound; the component C is external electron donor-organic silicon compound or the 1,4 aromatic diether. The catalyst has high catalytic activity, and can be adjusted in the range from 40,000 to 150,000 gPP/gCat when used in propylene polymerization. The polymer made therefrom has isotactivity of 80 to 99 percent and the molecular weight distribution can be adjusted in a wide range. The invention provides a novel method for preparing the 1,4 aromatic diether.