The invention relates to a catalyst used for 
olefin polymerization and a preparation method thereof. The preparation method is as follows: in a reactor, under the protection of 
nitrogen, adding an 
organic solvent and a 
titanium compound, cooling to-30 to-10 DEG C, adding a carrier, maintaining at-30 to-10 DEG C, and stirring for 30-40min; slowly heating to 100 to 120 DEG C, in the heating process, adding an 
electron donor compound, reacting at 100-120 DEG C for 30-40min, filtering a liquid, again adding the 
titanium compound, heating to 110 to 130 DEG C, maintaining at 110 to 130 DEG C for 30-40min, filtering the liquid, washing an obtained 
solid, and 
drying under vacuum to obtain a target product. In a 
magnesium halide alcohol adduct formation process, a forming agent and a particle form control agent are added, the 
particle size distribution of the obtained carrier is more concentrated, the carrier is used for preparing the catalyst, activity and 
hydrogen sensitivity of the catalyst can be improved when the carrier is used for 
olefin polymerization especially for propylene 
polymerization, the 
bulk density of an obtained 
polymerization product is moderate, and the 
polymerization product is basically free of abnormity materials.