Objective: To analyze the effects of different elastic modulus, thickness and tooth movement on the deformation of invisible dental appliance by finite element method (FEM), and to provide theoretical basis for orthodontics to formulate the orthodontic treatment scheme. Methods: Four finite element models of 12 kinds of invisible tooth appliance with four thickness and three elastic modulus were established. (1) the maximum von mises stress and shape variables of the appliance were analyzed by numerical simulation. (2) the deformation of the appliance is analyzed by applying the displacement load of tilt, parallel and low displacement to the optimal model. Results: (1) The maximum Von mises stress increases with the increase of the elastic modulus and the thickness of the invisible appliance. The shape variable decreases with the increase of appliance thickness. (2) When the tooth was tilted and moved parallel, the maximum deformation was found in the corresponding part of the tooth. Some of the corresponding parts of the immovable teeth are deformed to the lip convex side and some to the tongue side internal concave deformation, and the appliance deviates seriously to the top of the crown when the tooth is depressed and moved. Conclusions: (1) The optimum thickness was 0.75 mm, and the current elastic modulus of 816.31 MPA was suitable; (2) In the digital model, the tongue side of the teeth corresponding to the labial protruding part and the lip side of the tooth corresponding to the concave side of the tongue side are thickened, and the invisible appliance is made with the thickened digital model to optimize the appliance.