The invention discloses an olefin 
polymer-containing catalyst component used for 
olefin polymerization. The catalyst component is obtained by pre-polymerizing an 
olefin polymerization catalyst, an activator and olefin, and then storing offline, wherein the conditions of storing offline are as follows: the storage period is greater than 1 minute and less than 10 years, the storage temperature is -50 DEG C to 80 DEG C, A(Time, Temp) of the catalyst component is greater than or equal to A(0-1, Temp)*50%(g 
polymer / g reactive 
metal center), and when the fluctuation range of the storage temperature is within -10 DEG C to 10 DEG C, A(Time2, Temp) is greater than or equal to A(Time1, Temp)*50%(g 
polymer / g reactive 
metal center). The invention also discloses a catalyst used for 
olefin polymerization, comprising the olefin polymer-containing catalyst component, an 
aluminium compound and optionally, an external 
electron donor compound. When the catalyst component and the catalyst are applied in olefin 
polymerization, the problems of aggregation, 
caking and the like caused by catalyst particle breakage and local hot points can be avoided, and the 
fine powder content can be reduced.