Geopolymers are man-made aluminosilicate materials with many exceptional properties. The preparation of geopolymer, using SDRMS as main raw material, lime (CaO) and gypsum (CaSO4ּ2H2O) as activators in analytical grade, was carried out, and the hydration products of which were characterized by XRD and SEM simultaneously in this study. The results revealed that compressive strength of geopolymer paste obtained by the combined excitation of lime and gypsum, was higher than that obtained by only excitation of lime. The former was in the range of 46-70 MPa, the latter was 5–28 MPa after 28d maintenance of geopolymer paste. The highest strength of 70MPa was obtained when the weight ratio of SDRMS/ lime/ gypsum was at 70:20:10 in the geopolymer paste. By the combined excitation of lime and gypsum, the SiO2 and Al2O3 in SDRMS were changed into the hydrates of ettringite, gismondine, killalaite and other based on XRD, which were observed with the acupuncture-like, fibrous, tabular and dendritic microstructure based on SEM.