Objective To explore the clinical effect of maxillary protraction combined with spiral arch expansion device is definite. Meanwhile, it has high application value in the treatment of children with skeletal class Ⅲ malocclusion in mixed dentition. in the treatment of skeletal class Ⅲ malocclusion in mixed dentition. Methods A total of 70 children with skeletal class Ⅲ malocclusion in mixed dentition admitted to our hospital from May 2021 to May 2022 were selected as the research objects. According to the order of treatment, they were divided into control group and study group, with 35 children in each group. The control group was treated with maxillary protraction, and the study group was treated with maxillary protraction combined with spiral arch expansion device. The clinical efficacy, lateral cephalogram index and upper airway space were compared between the two groups. Results The total effective rate of treatment in the study group was 94.29%, which was higher than 74.27% in the control group (P<0.05). There was no significant difference in SNA, SNB, Ptm-A, Y-axis angle and N-Me between the two groups after treatment (P>0.05). After treatment, ANB, FH-MP, SN-PP, U1-SN, L1-MP and ANS-Me in the study group were higher than those in the control group (P<0.05). After treatment, PNS-R in both groups was higher than that before treatment, and SPL was lower than that before treatment (P<0.05), but there was no significant difference in PNS-R, PAS, V-LPW and SPL between the two groups after treatment (P>0.05). Conclusion Maxillary protraction combined with spiral arch expansion device treatment can effectively expand the upper airway space, reduce the lower part, maintain the stability of the upper and lower jaws and dentition, and the curative effect