Abstract: Objective: To clarify whether DAPT (a γ-secretase inhibitor) could inhibit the Notch signaling pathway in the cementoblast OCCM30. To investigate the impact of DAPT on the proliferation of the cementoblast and the mechanism behind. Methods: The OCCM30 cells were cultured with γ-secretase inhibitor DAPT. On day 2, 4 and 6, RT-PCR was conducted to detect the expression of the Notch signaling pathway genes (Hes-1 and Hey-1) and cell cycle related genes (Cyclin D and Cyclin E) and flow cytometry was used to investigate the impact of DAPT on the cell cycle of OCCM30. On day 8, the CCK-8 was carried out for the detection of the proliferative activity of the OCCM30. Results: Compared to the control group, the expression level of Hes-1, Hey-1, Cyclin D and Cycin E in the experimental groups decreased (P<0.05) while the G1/G0 cell proportion increased (P<0.05). From day 2 to day 8, the proliferative activity of the cells in the experimental groups decreased significantly (P<0.05). The proliferative activity of the OCCM30 in the higher DAPT concentration group was lower than that in the lower DAPT concentration group, both of which were significantly lower than the control group (P<0.05).Conclusion: DAPT effectively inhibited the proliferative activity of the OCCM30. The mechanism behind that could be the inhibitory effect of the DAPT on the Notch signaling pathway, down-regulating the expression of the cell-cycle related genes.