Self-setting biomaterials are widely used for tissue repair and regeneration. Calcium sulfate hemihydrate has been used for many years as a self-setting biomaterial due to its good setting properties. However, too fast a degradation rate and lack of bioactivity have limited its application in orthopaedic field. Herein, tricalcium silicate was introduced into calcium sulfate hemihydrate (CaSO(4).1/2H(2)O) to form a calcium sulfate hemihydrate-based composite, and its behavior as a cement was studied in comparison with pure calcium sulfate hemihydrate. The results indicated that the workability and setting time of the composite pastes are higher than those of pure CaSO(4).1/2H(2)O, and the composite pastes showed much better short- and long-term mechanical properties than those of pure CaSO(4).1/2H(2)O. Moreover, the biphasic specimens showed significantly improved bioactivity and degradability compared with those of pure CaSO(4).1/2H(2)O, indicating that the composite cements might have a significant clinical advantage over the traditional CaSO(4).1/2H(2)O cement.