Objective To investigate the aesthetic effect of penetrating resin combined with micro-grinding technology in the repair of patients with white spot lesions after orthodontic treatment. Methods A total of 60 patients with white spot lesions on orthodontic posterior teeth admitted to Xining Stomatological Hospital from January 2019 to February 2022 were selected as the research objects. They were divided into routine group and experimental group randomly, with 30 patients in each group. The routine group was treated with micro-grinding technology alone, and the experimental group was treated with penetrating resin technology on the basis of the conventional group. The repair effect, lesion condition, color and hardness of the affected teeth were compared between the two groups. Results The total effective rate of repair in the experimental group was higher than that in the routine group (P <0.05). After treatment, the lesion area ratio of the experimental group was lower than that of the routine group, and the white spot lesion software and subjective scores were higher than those of the routine group (P <0.05). After treatment, SMH in the experimental group was higher than that in the routine group, and L* value was lower than that in the routine group (P <0.05). Conclusion The repair effect of penetrating resin in patients with white spot lesions after orthodontic treatment is ideal, which can reduce the lesion area, improve the lesion and the color and hardness of the affected teeth, and is worthy of clinical application.