Abstract: Abstract: Objective To evaluate the remineralization effect of incipient enamel caries after treated with fluoride iontophresis in vitro. Methods All specimens of artificial incipient enamel caries were subjected to a pH-cycling process for 7 d and a remineralizing process for 2 d. Different groups were examined with scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).Result Micrographs of SEM showed a rough etching enamel surface in the control group, while those in 1.23% APF gel group and FI group showed relatively homogeneous surfaces. Fluorescence lesion area and lesion depth were significantly less (pH,A<0.001) in APF gel group （38230.87±2704.43）μm2,（40.51±4.26）μm and FI group （43407.27±4666.09）μm2,（41.90±6.83） μm than those in control group, although no statistical differences could be detected between the two treatment groups（PH=0.912，PA=0.679）. Conclusion Fluoride iontophoresis was effective in promoting incipient enamel remineralization, although no differences could be observed between 1.23% acidulated phosphate ?uoride gel.