Preparation method of double-peak pore-structure carrier silica gel

A method for preparing double-peak pore-diameter-distribution silica gel with an inorganic silicon source and an organic silicon source as raw materials through a two-stage gel reaction. In the method, a first stage of the reaction includes a step of performing a sol-gel reaction with the organic silicon source to prepare pores with average pore size distribution being 2-20 nm by means of adjustment of raw material proportion, reaction temperature and pH value; and a second stage of the reaction includes a step of performing the sol-gel reaction to the inorganic silicon source by means of adjustment of the pH value, the reaction temperature and an aging time to obtain macropores being 10-50 nm in average pore size distribution through adjustment and control of the pore size of the silica gel in the second stage, and then the carrier silica gel is prepared by means of steps of water washing and drying, wherein the difference of the average pore size of the two peaks is larger than 10 nm. By means of the carrier, a catalyst, when being used for catalyzing olefin polymerization, can be used for preparing olefin polymer being wide in molecular weight distribution.