A catalyst component for olefin polymerization is provided. The catalyst component comprises magnesium halide in an active state, a titanium compound containing at least one Ti-halogen bond and supported by the magnesium halide, and at least one unsaturated ring substituted diacid ester compound of the general formula (I) that is supported by the magnesium halide. The catalyst component has excellent activity. The prepared polymer has high isotacticity.