Objective: To explore the effect of arch expansion combined with straight wire orthodontic appliances in the treatment of maxillary arch stenosis with dental arch misalignment. Method: A random number table method was used to divide 120 patients with maxillary arch stenosis and malocclusion admitted to the hospital from December 2023 to December 2025 into two groups, n=60。 The group names include: control group and study group, which were treated with straight wire appliance and expanded arch combined with straight wire appliance, respectively. Using statistical software, analyze the observation indicators after implementing different treatment plans, including periodontal indicators, arch changes, projection measurements, and incidence of complications. Result: After treatment, the periodontal indicators in the study group were lower than those in the control group (P<0.05); The inter group differences in dental arch changes showed that the study group had better maxillary length and width than the control group, and the differences had comparative value (P<0.05); Statistical analysis showed that the projection measurement results of the research group were lower than those of the control group in all indicators (P<0.05); The difference in incidence rate between the two groups showed no significant difference in proportion (P>0.05). Conclusion: The combination of arch expansion and straight wire appliance treatment has a better improvement effect on patients" periodontal indicators, with positive significance for arch changes and projection measurements, and no serious complications have occurred, indicating high safety.