Abstract: Objective: To study the effect of Nano. Ag-TiO₂ on the antibacterial property of glass ionomer cements. Methods: Nano.Ag-TiO₂ was added into the glass ionomer cement with the mass ratio of 0%, 1%, 2%, 3%, 4% and 5%. After stirred by mechanical means, the mixed cement was filled in the mold quickly. The inhibitory effect and antibacterial durability of specimen were observed on Streptococcus mutans. Results: With the increased content of Nano. Ag-TiO₂, the inhibition rate of mixed cement on the Streptococcus mutans raised, which was significant different from the control group (P<0.05); The inhibition rate of the natural aging group did not change significantly. The inhibitory rate of the group with 3% Nano.Ag-TiO₂ was more than 90%. Conclusion: Glass ionomer cement added with Nano.Ag-TiO₂ has good antibacterial effects with lasting stability.