In this paper, coal slag, granite powder and high calcium fly ash were used as the main raw materials, and NaOH was used as the activator to prepare geopolymer. On the basis of single factor experiment, the Box-Behnken Design model in response surface method was used to analyze the effects of different solid waste mass blending ratios on the compressive strength of geopolymer. The phase composition and microstructure of the geopolymer were analyzed by XRD, FTIR and SEM. The results show that the order of the influence of the mass ratio of each solid waste on the response value is high calcium fly ash, coal-fired slag, granite powder. The interaction between granite powder and high calcium fly ash is significant. The optimal raw material ratio parameters obtained by response surface optimization are as follows: the mass ratio of coal slag is 1.8, the mass ratio of granite powder is 0.8, and the mass ratio of high calcium fly ash is 7.0. Under this ratio, the average compressive strength of geopolymer at early stage (7 d) can reach 22.73 MPa. Coal slag, granite powder and high calcium fly ash cooperate with each other to form amorphous gel phase and zeolite minerals through geopolymerization reaction, which provides strength for geopolymer. The grading effect of granite powder and high calcium fly ash makes the structure of geopolymer denser. This study can provide a reference for the synergistic disposal of bulk and multi-solid waste.