Objective To observe the clinical effect of fiber post and core crown in repairing large area defect of teeth. Methods From November 2021 to November 2022, 80 patients with large area defect of teeth were selected as the research objects, and they were randomly divided into control group and observation group, with 40 patients in each group. The control group was treated with cast metal post and core crown restoration, and the observation group was treated with fiber post and core crown restoration. The clinical efficacy, chewing and occlusal function, gingival function and complications were compared between the two groups. Results The success rate of repair in the observation group was higher than that in the control group (P<0.05). The chewing efficiency and bite force of the observation group were better than those of the control group (P<0.05). After treatment, the bleeding index, gingival index and plaque index of the observation group were lower than those of the control group (P<0.05). The incidence of complications in the observation group was lower than that in the control group (P<0.05). Conclusion The success rate of fiber post and core crown restoration in patients with large area defect of teeth is higher, which can improve the patient's chewing and occlusal ability, improve the patient's gingival function index, and the incidence of complications is lower.