Abstract: Objectvies To investigate the feasibility of using small intestinal sub mucosa(SIS) as pulp capping agent. Methods SIS and medical films of PLA were used as cytoskeletons and compositely cultured with human dental pulp cells(HDPCs). The rate of cells adhesion and proliferation index were measured. Compare the levels of ALP activity and the sizes of calcium noduls in the two groups to evaluate the mineralization capacity of HDPCs. Results The rate of cell adhesion in SIS group at 24h was 64.36%, which was significantly higher than that of PLA group (P <0.05). The cell proliferation index in SIS group after 3,5,7 d was 23,18.9,17.9 separately, which was significantly higher than that in PLA group(P<0.05). The levels of ALP activity in SIS group were higher than those in PLA group on 7,14,21 d (P<0.05).The calcium nodules appeared in SIS group on 28d，which did not appear in PLA group. Conclusions SIS is of good biocompatibility and can promote proliferation and mineralization of human dental pulp cells in vitro. Therefore, SIS is a new feasible pulp capping material.