Objective To investigate the effect of glass fiber post combined with composite resin in repairing tooth defect. Methods A total of 100 patients with tooth defects admitted to our hospital from January 2020 to January 2022 were selected as the research objects. They were randomly divided into control group and observation group, with 50 patients in each group. The control group was repaired with metal post, and the observation group was repaired with glass fiber post combined with composite resin. The success rate of repair, repair condition, clinical indicators, and complication rate were compared between the two groups. Results The success rate of repair in the observation group was higher than that in the control group, the difference was statistically significant (P<0.05). The complete rate of tooth repair and the appropriate rate of edge in the observation group were higher than those in the control group, and the rate of tooth loosening was lower than that in the control group, the differences were statistically significant (P<0.05). The scores of aesthetics, fixation function and chewing function in the observation group were higher than those in the control group, and the ALP test data were lower than those in the control group, the differences were statistically significant (P<0.05). The incidence of complications in the observation group was lower than that in the control group, the difference was statistically significant (P<0.05). Conclusion Glass fiber post combined with composite resin can achieve excellent repair effect in patients with tooth defect, and it has high aesthetics and strong fixation function. Meanwhile, it can improve the chewing function of patients and has high safety, which is worthy of clinical application.