Objective:To investigate the mechanism of the effect of Chinese nutgall on enamel demineralization.Method:Set non-organic enamel model.Treat normal enamel samples and non-organic enamel samples with 30 mg/ml Chinese nutgall,2% NaF,38% Ag(NH_3)_2F,10% AgNO_3 and deionized water respectively.Form enamel lesions with chemical demineralization model,collect demineralization solution of each group,measure the content of Ca and P.Analysis enamel mineral loss and lesion depth with microradiographic system.Result:Same with the results of 38% Ag(NH_3)_2F and 10% AgNO_3,30 mg/ml Chinese nutgall has a much better effect of inhibiting demineralization on normal enamel than on non-organic enamel.There are no significant difference between the effect of 2% NaF on normal enamel and that on non-organic enamel.Conclusion:Enamel matrix may inhibit demineralization under certain circumstance;Chinese nutgall shows the effect of inhibiting enamel demineralization through acting on enamel matrix.