The invention provides a catalyst component for olefin polymerization, a preparation method and an application thereof. The catalyst compound provided by the invention contains at least an organo-magnesium compound, at least a liquid titanium-containing compound, at least a hydroxy compound, at least a chlorine-containing organo aluminium compound and at least a reaction product of an agent for shaping and assisting precipitation, wherein the agent for shaping and assisting precipitation is a polystyrene block polybutadiene polymer. The catalyst prepared in the invention has good hydrogen regulation performance, and simultaneously has good particle form and distribution and higher bulk density of the polymer, therefore making the catalyst more applicable to be used in polymerization technological devices of gas phase, slurry and the like.