Objective To analyze the application effect of bulk-filled resin in the repair of dental caries in children. Methods A total of 80 children with dental caries admitted to People’s Hospital of Fengtai County from August 2020 to August 2021 were selected as the research objects. They were divided into control group and experimental group by random number table method, with 40 cases in each group and 58 affected teeth. The control group received traditional resin repair treatment, and the experimental group received bulk-filled resin treatment. The clinical efficacy, pulp, periodontal related indicators, complications and filler damage consumption were compared between the two groups. Results There was no significant difference in the total effective rate between the two groups (P>0.05). After treatment, the periodontal probing depth, bleeding index and plaque index in the experimental group were lower than those in the control group, but the difference was not statistically significant (P>0.05). The incidence of complications in the experimental group was 5.00%, which was lower than 20.00% in the control group (P<0.05). The total filling damage rate of the experimental group was 5.17%, which was lower than 20.69% of the control group (P<0.05). Conclusion The application of bulk-filled resin in the repair of dental caries in children is effective, which can effectively improve the pulp, periodontal related indicators and filler damage consumption. Meanwhile, it is conducive to the recovery of dental function, and has fewer complications and higher safety after repair.