Catalyst carrier for olefin polymerization, solid catalyst component and catalyst

The invention relates to a dialkoxyl magnesium carrier, which is a product produced by reflux reaction of magnesium, an alcohol and mixed halogenating agents under an inert atmosphere. The mixed halogenating agents are iodine and magnesium chloride, and the weight ratio between iodine and magnesium chloride is 0.05:1-1:0.01. The dialkoxyl magnesium carrier is spheroid, its particle size distribution is uniform, the particle morphology is excellent and the bulk density is high. A solid catalyst component and a catalyst based on this carrier for olefin polymerizationare also provided, and olefin polymer having wide molecular weight distribution, good stereoregularity, excellent particle morphology and low content of fine powder can be obtained.