Objective To evaluate the effect of defluoridating agent combined with cold-light bleaching on whitening effect and tooth sensitivity in patients with dental fluorosis. Methods A total of 62 patients with dental fluorosis admitted to our hospital from January 2023 to August 2024 were selected as the research subjects. According to the random number table method, they were divided into the control group and the observation group, with 31 patients in each group. The control group was treated with the simple Beyond cold-light bleaching technology, and the observation group was treated with the defluoridating agent combined with the Beyond cold-light bleaching technology. The whitening effect, tooth sensitivity, dental surface lesion area, tooth roughness and microhardness, mental state and aesthetic effect satisfaction were compared between the two groups. Results The total effective rate of treatment in the observation group was 100.00%, which was higher than 87.10% in the control group, and the difference was statistically significant (P <0.05). The proportion of patients with no sensitivity after treatment in the observation group was higher than that in the control group, and the difference was statistically significant (P <0.05). The area of dental surface lesions in the observation group was lower than that in the control group at 30 and 90 days after treatment, and the difference was statistically significant (P <0.05). After treatment , the tooth roughness in the observation group was lower than that in the control group, and the microhardness in the observation group was higher than that in the control group, and the differences were statistically significant (P <0.05). After treatment, the scores of SAS and SDS in the observation group were lower than those in the control group, and the differences were statistically significant (P <0.05). The satisfaction rate with the aesthetic effect in the observation group was higher than that in the control group, and the difference was statistically significant (P <0.05). Conclusion The application of defluoridating agent combined with cold-light bleaching technology in the treatment of dental fluorosis can repair and protect the dental health of patients, with good whitening effect. It can also improve the negative psychology of patients and enhance their comfort, which is worthy of clinical application.