Abstract: The alite-sulphoaluminate clinker was made by use of raw materials got from Qinghai Province, China. The clinker combines the advantages of Portland cement clinker and sulphoaluminate cement clinker and can excite the activity of mineral admixtures such as fly ash and slag more easily because of its alkaline and sulfate dual activation. Based on those properties of the clinker, a kind of compound cement, high-activity alite-sulphoaluminate cement (HAASC) was prescribed. By means of microstructural analyses, the hydration reaction mechanism of HA-ASC was discussed, and the principle of dominant complementation effect in a complex cementitious system was stated. It is proved that the concentration of Ca(OH)₂ in hardened HAASC paste is much lower than that in ordinary Portland cement paste, and its long-term strength is improved with an appropriate crystal/gel ratio because of its particular mineral composition of clinker and dual activation to slag and fly ash, however its early strength is somewhat lower.