A novel tricalcium phosphate Ca3(PO4)2 and calcium silicate CaSiO3 (TCP/CS) bone cement was developed and its mechanical properties and biocompatibility were evaluated from various proportions of TCP/CS composites which yield an injectable, self-solidified and degradable alternative biomaterial. The Osteoblasts (OB) were added into the TCP/CS composite disks and the properties of OB such as adhesion, proliferation, morphology and differentiation were observed. The solidification time of TCP/CS increases as the content of CS increases. The injectability of TCP/CS composite improves dramatically comparing that of TCP paste. The compressive strength of TCP/CS composites is greatly stronger than that of TCP alone. Furthermore, the degree of cell attachment, proliferation and differentiation, as well as biocompatibility significantly improves upon addition of CS into TCP. The TCP/CS composite with injectability possesses high strength and good biocompatibility, it might become a new biomaterial for vertebroplasy in the treatment of osteoporotic compressive fractures.