Objectives: Analyzing the influence of different filling methods on the microleakage of posterior teeth during the treatment of bulk resin filling. Methods: From January 2019 to January 2020, 68 patients with posterior tooth filling (123 teeth) in our hospital were selected and randomly assigned into three groups (A, B, and C), with 41 teeth in each group. Group A received bulk posterior teeth filling resin treatment, group B received Charisma® resin filling treatment and group C received FX-? filling treatment. The curative effect and microleakage of posterior teeth between the groups were compared. Results: Comparison of treatment efficiency in group A (97.56%), group B (85.37%) and group C (73.17%) shows that P?0.05?comparison of microleakage value and operation time of group A, group B and group C shows that P?0.05. Conclusions: In resin filling treatment, bulk posterior tooth filling resin material should be selected for its high hardness, strong edge adhesion, and natural effects.