Carrier for preparing olefin polymerization catalyst and preparation method thereof

The invention relates to a carrier for preparing an olefin polymerization catalyst. The carrier is a magnesium-containing compound shown as a general formula (I). In the structural formula (I), R1 is C1 to C12 linear or branched alkyl; R2 and R3 are the same or different, and are hydrogen or C1 to C5 linear or branched alkyl, wherein hydrogen on the alkyl can be optionally substituted by a halogen atom; Xs are chlorine or bromine, and one of the Xs can be substituted by C1 to C14 alkyl or alkoxyl, C6 to C14 aryl or aryloxy; and m is 0.1 to 0.9, n is 0.1 to 1.9, and p+m+n=2. In a differential scanning calorimetry (DSC) graph of the magnesium-containing compound, a remarkable exothermic peak is generated in the range of between 70 and 250 DEG C, a peak value of the exothermic peak is generated in the range of between 100 and 200 DEG C, and an exothermic enthalpy related to the exothermic peak is more than 40joules/gram.