The present invention provides an olefin polymerization catalyst component, a catalyst system, a prepolymerization catalyst composition and an olefin polymerization method, which belong to the field of olefin polymerization catalysts. The catalyst component contains magnesium, titanium, halogen, and an internal electron donor, and the internal electron donor comprises a compound A, a compound B and a compound C, wherein the compound A is selected from a hydroxybenzoyl compound represented by formula (I), the compound B is selected from one or more of an ester compound other than the compound A and an ether compound, and the compound C is selected from an alkoxysilane represented by formula RnSi(OR6)4-n, and wherein, a content of the compound A may be zero. When the catalyst system comprising the catalyst component and a co-catalyst component or a reaction product of the two, or a prepolymerization catalyst composition prepared by further prepolymerization is used for olefin copolymerization, an excellent olefin copolymerization ability is exhibited, and a good polymerization activity, stereospecificity and hydrogen adjustment sensitivity are maintained; in addition, polymer particles that are obtained have a good morphology and a high sphericity, and contain less fine powder.