Objective To explore the relationship between oral bad habits and malocclusion in children, and to evaluate its effect by preventive and corrective measures. Methods From February 2018 to February 2021, 100 children with malocclusion who underwent oral examination in our hospital were selected as the observation group, and 100 normal children in the same period were selected as the control group. The control group was divided into control group 1 and control group 2 by random number table method, with 50 children in each group. The observation group was divided into observation group 1 and observation group 2, with 50 children in each group. The control group 1 received preventive measures intervention, the observation group 1 received corrective measures intervention, the control group 2 and the observation group 2 did not receive preventive and corrective measures intervention, and the preventive effect and corrective effect in the group were compared. Results The total incidence of oral bad habits in the observation group was 68.00%, which was higher than 20.00% in the control group, the difference was statistically significant (P<0.05). The total incidence of malocclusion in control group 1 was lower than that in control group 2, the difference was statistically significant (P<0.05). The width of upper arch, the width of lower arch, the crowding degree of upper arch and the crowding degree of lower arch in the observation group 1 were better than those in the observation group 2, the difference was statistically significant (P<0.05). Conclusion Children's bad oral habits will increase the incidence of malocclusion. Preventive measures for children with oral health can reduce the risk of malocclusion. Timely corrective treatment for children with malocclusion is conducive to relieving dentition crowding, establishing a good occlusal relationship and improving the correction effect. 【Key words】Children's bad oral habits; Malocclusion; Prevention and correction