Objective To explore the therapeutic effect of glass fiber reinforced resin post and core repair for residual crown and root. Methods A total of 72 patients who underwent residual crown and root repair in our hospital from January 2019 to January 2023 were selected as the research objects. They were divided into observation group and control group by random number table method, with 36 patients in each group. The control group was treated with metal casting post and core repair, and the observation group was treated with glass fiber reinforced resin post and core. The repair effect, tooth health status, language function, chewing function and adverse reactions were compared between the two groups. Results The total effective rate of repair in the observation group was 94.44%, which was higher than 77.77% in the control group (P <0.05). The levels of GI and BI in the observation group were lower than those in the control group (P <0.05). The language function and chewing function of the observation group were higher than those of the control group (P <0.05). The incidence of adverse reactions in the observation group was 2.77%, which was lower than 19.44% in the control group (P <0.05). Conclusion Glass fiber reinforced resin post and core is effective in repairing residual crown and residual root. Compared with metal casting post and core, it can effectively improve the repair effect, improve the patient's language and chewing function. At the same time, the probability of various complications in patients after repair is low. The health status of teeth has been effectively guaranteed, which is conducive to promoting recovery and is worthy of clinical application.