Objective To investigate the effect of light-curing resin surface treatment agent on the initial color relapse of cold-light bleaching teeth. Methods A total of 80 isolated teeth collected in our hospital from September 2022 to January 2023 were included in the study. They were randomly divided into group A and group B, with 40 teeth in each group. Each group was randomly divided into two subgroups (group A1, group A2, group B1 and group B2), with 20 teeth in each group. Both groups were treated with cold-light bleaching. Group B was treated with light-cured resin surface treatment agent after cold-light bleaching. Group A did not do any treatment, and then aging test was carried out. Groups A1 and B1 placed the isolated teeth in distilled water for 42 days. Groups A2 and B2 were placed in tea for 42 days. The color difference was measured by a colorimeter and the microstructure of the sample surface was observed by a microscope. Results There was no significant difference in color difference between groups A1 and B1 when the isolated tooth samples were soaked in distilled water at different times ( P >0.05).There was a significant difference in the color difference between the isolated tooth samples soaked in tea water between groups B2 and A2 at different times ( P <0.05).Conclusion Applying light-curing resin surface treatment agent after cold-light bleaching can make the enamel surface smoother and reduce the initial color relapse, which is worthy of further promotion.