Dicalcium silicate/zirconia composite coating with 70 wt.% zirconia and 30 wt.% dicalcium silicate was prepared by plasma spraying. In vitro behaviors of human osteoblast cells on the coating were studied. As a result of rapid exchange of Ca and H in the culture media and dissolution of the dicalcium silicate component from the coatings, a large amount of Si-OH functional group was produced on the coating. These OH bonds were favorable to the adhesion of proteins and cells attachment and thus, the good cytocompatibility of the coatings. Honeycomb-like Ca-P minerals were formed on the coating surface after only 1 day incubation in the culture media. The deposition rate of the Ca-P minerals was greatly improved by the existence of proteins. It may be attributed to the increased Ca ion concentration in the culture media resulting from the dissolution of dicalcium silicate and the good protein adhesion properties of the coating.