A DRA monomer is an intermediate produced in production process of a petroleum drag reducer. The invention relates to a compounding method for a DRA monomer suspension liquid. The method comprises the following steps: 1, soaking the DRA monomer in a liquid nitrogen for cooling the DRA monomer to reach the temperature below the glass transition temperature; 2, mixing the cooled DRA monomer at the temperature below the glass transition temperature with a wrapping agent, and crushing until the granularity of the DRA monomer is 80 mesh; 3, re-adding the wrapping agent into the crushed DRA monomer, then adding into a container, and stirring at the room temperature to obtain a mixture; 4, homogenizing the mixture obtained in step 3 with the wrapping agent and a homogenized agent in a homogenizing machine after the mixture returns to the room temperature so as to obtain the stable DRA monomer suspension liquid. By using the invention, the generation of agglomeration in the DRA monomer suspension liquid can be effectively reduced, so that the good fluidity and drag reduction effects of products can be ensured.