Abstract: Objective To observe the correction of Angle’s II1 malocclusion in growth and development stages with Twin-block appliances, and discuss the treatment mechanism. Methods Use Twin-block appliances for 18 cases of Angle’s II1 malocclusion in growth and development stages, 10 male and 8 female, 10 to 13 years old, with no history of malocclusion. Results After 20 to 24 months’ treatment, the 18 patients’ anterior tooth overbite, and covering relation were nearly normal, molar relationship was neutral, and lateral profile of soft tissue significantly improved. Conclusions Twin-block appliances have obvious effect on Angle’s II1 malocclusion in growth and development stages