Objective To explore the effect of FR Ⅲ appliance on soft and hard tissue indicators in children with malocclusion during mixed dentition period. Methods A total of 40 children with malocclusion in mixed dentition period admitted to Shuyang Zhongxing Hospital from January 2023 to January 2025 were selected as the research subjects, and they were divided into group A (n=20) and group B (n=20) by the random number table method. Group A was given conventional orthodontic treatment, and group B was given FR Ⅲ appliance treatment. The soft tissue indicators, hard tissue indicators and clinical efffcacy were compared between the two groups. Results After treatment, the UL-EP and NLA in group B were higher than those in group A, while the LL-EP was lower than that in group A (P<0.05). After treatment, the SNA and SN-MP in group B were higher than those in group A, while the SNB was lower than that in group A (P<0.05). The total effective rate of group B (95.00%) was higher than that of group A (70.00%) (P<0.05). Conclusion FR Ⅲ appliance can effectively improve the soft and hard tissue indicators of children with malocclusion during mixed dentition period, and increase the total treatment effective rate, with superior overall effects compared with conventional orthodontic treatment.