Objective To compare the effects of three filling materials for class Ⅰ cavity of the posterior teeth. Methods From January 2021 to January 2022, 60 patients with class Ⅰ cavity of mandibular first molar admitted to Huangpu District Dental Disease Prevention and Control Institute were randomly divided into group A, group B and group C, with 20 patients in each group. Group A was filled with Dyract AP "seal method", group B was filled with SE BOND AP-X "spillover hole seal method", and group C was filled with 3M Z250. After 12 months of follow-up, the marginal seal, curing degree and satisfaction of the three groups were compared. Results There was no significant difference in marginal seal among the three groups (P>0.05). The curing degree of group C was better than that of group A and group B, and the difference was statistically significant (P <0.05). The satisfaction scores of solid, color coordination, edge coloring and surface morphology in group C were higher than those in group A and group B, and the differences were statistically significant (P<0.05). Conclusion Dyract AP "seal method" SE BOND AP-X "spillover hole seal method" and 3M Z250 have no significant difference in the marginal sealing of class Ⅰ cavity of the posterior teeth, while 3M Z250 filling is superior to the other two filling methods in the degree of curing and satisfaction of class Ⅰ cavity of the posterior teeth. Clinically, appropriate filling materials can be selected according to the specific conditions of patients and the differences of individual qualities.