Objective To investigate the protective effect from fluoride foam and fluor protector on primary teeth enamel demineralization. Methods Sixty intact mandible primary insicors were divided into A/B/C group according to treatment on fixed enamel surface by different reagents.Group A :fluoride foam,Group B:fluoride protector and Group C:deionized water.The specimens were put in saturated acid buffer demineralizationfor 72 hours,experiment enamel surface was observed by scanning electron microscopy(SEM) to assess microscopic change,then the quantity of calcium in part saturated acid buffer demineralization was detected by atomic absorption spectrophotometer and analyzed statistically. Results In light of Ca²⁺ in saturated acid buffer demineralization,there were significant differences between A/C group and B/C group,and between A/B group (P<0.05).SEM observation of enamel surface showed that demineralization of C group was more obviously than A and B group,in which mineral compound could be detected. Conclusions Fluoride foam and fluor protector can both improve the resistance to acid of the primary teeth enamel and promote mineralization process.Fluoride protectorplays a stronger role than fluoride foam in protecting primary teeth.