The invention relates to a catalyst component for vinyl polymerization and a preparation method thereof. The catalyst component comprises a kind of magnesium compound, a kind of titanium compound, a kind of organic alcoholic compound and a kind of organosilicon compound, wherein the organosilicon compound has the following structure that: in the organosilicon compound, R1 is a substituent group containing 3 to 20 carbon atoms and carrying different functional groups, the functional groups are ester, epoxy, halogen, amine, ether, ketone and the like, and R2, R3 and R4 are aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aryl groups and derivatives thereof. The catalyst has the advantages of higher catalytic activity, higher hydrogen-adjusting sensitivity, narrow grain size distribution of polymers, high bulk density and the like.