catalyst component, catalyst, prepolymerized catalyst and olefin polymerization process

catalyst component, prepolymerized catalyst and olefin polymerization process. The present invention provides catalyst component for polymerization of olefin ch ~ 2 ~ = chr and its catalyst, wherein r is hydrogen or cl-Cl 2 alkyl or aryl, said catalyst component contains magnesium, titanium, halogen and electron donating compounds (a) , said electron donor compounds (a) are selected from at least one diester compound of the following formula (i), said catalyst component also optionally contains electron donor compounds (b) and / or (c), said electron donor compounds ( b) are selected from dibasic aliphatic carboxylic acid ester and dibasic aromatic carboxylic acid ester, said electron donor compounds (e) are selected from the 1,3-diether compounds of formula (v), wherein r , r ~ 1 ~ and a are defined as in the report, where r ~ i ^ -r ^ viii ^ are defined as in the report.