Objective To explore the effect of preformed crown restoration on facial aesthetics in patients with large-area carious lesions of primary molars. Methods A total of 60 patients with large-area carious lesions of primary molars admitted to the Department of Stomatology, the First Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2024 to June 2025 were selected as the research subjects, and they were divided into the control group and the observation group by the random number table method, with 30 patients in each group. The control group received conventional resin fflling treatment, and the observation group received preformed crown restoration treatment. The facial aesthetics, jaw development indicators, marginal adaptation, success rate of proximal contact relationship and masticatory function were compared between the two groups. Results The facial aesthetic score of the observation group at 6 months after restoration was higher than that of the control group (P<0.05). The alveolar bone height and jaw development level of the observation group at 6 months after restoration were better than those of the control group (P<0.05). The marginal adaptation of the observation group was better than that of the control group (P<0.05). The success rate of proximal contact relationship in the observation group was higher than that in the control group (P<0.05). The maximum occlusal force and masticatory efffciency of the observation group at 6 months after restoration were better than those of the control group (P<0.05). Conclusion Preformed crown restoration can effectively repair large-area carious lesions of primary molars, improve facial aesthetics, promote normal jaw development, enhance masticatory function, ensure favorable marginal adaptation of restorations, restore stable proximal contact, and achieve a high clinical success rate.