Objective To analyze the effect of fiber post combined with zirconia crown restoration on aesthetic effect and masticatory function in patients with extensive tooth defect. Methods A total of 92 patients with extensive tooth defect admitted to the Department of Stomatology of the First People's Hospital of Guiyang from January 2022 to December 2023 were selected. According to the random number table method, they were divided into the control group and the observation group, with 46 patients in each group. The control group was treated with metal post and porcelain-fused-to-metal crown restoration, and the observation group was treated with ffber post combined with zirconia crown restoration. The aesthetic effect, masticatory function, periodontal health indicators and complication rate were compared between the two groups. Results The scores of aesthetic effect in the observation group were higher than those in the control group (P<0.05). At 1 year after restoration, the masticatory function of the observation group was better than that of the control group (P<0.05). At 1 year after restoration, the periodontal health indicators of the observation group were all better than those of the control group (P<0.05). The incidence of complications in the observation group (4.35%) was lower than that in the control group (19.57%) (P<0.05). Conclusion Fiber post combined with zirconia crown restoration for extensive tooth defect can effectively improve masticatory function and periodontal health status, reduce the incidence of complications, and enhance aesthetic effect.