Abstract: To investigate the pattern of influence of industrial by-products such as flue gas desulfurization gypsum（FGDG）, fly ash（FA）, and limestone（LS） on the strength and pH of calcium sulphoaluminate cement（SAC）, FGDG, FA and LS were used as solid waste admixture to modify SAC clinker and the modified SAC cured for 7 d and 28 d was tested for unconfined compressive strength（UCS） and pH. Response surface methods（RSM） were also used to develop regression models for the UCS and pH of the modified SAC. The effect patterns of each factor on UCS and pH were analyzed. The results of the study show that both the UCS and pH of the modified SAC are influenced by the single and multifactorial effects of FGDG, FA, and LS. The interaction between FGDG and LS, LS and FA has a significant effects on UCS_{7 d} and UCS_{28 d}. The interaction between LS and FA, FGDG and FA has a significant effects on pH_{7 d}, but not on pH_{28 d}. The RSM-BBD multi-objective optimization method are used to optimize industrial by-products, the established regression model has high reliability and accuracy, and the optimal addition ratio meeting the requirements of high strength and low alkali-nity is obtained, and the error of the test and the predicted values is small under this ratio.