Objective By biomechanical research on dental cast with invisible orthodontic appliances, analyze the features of the orthodontic forces and effect of invisible appliances.Method A three-dimensional FE model of dental cast was set up, which includes teeth￡?periodontal membrane and alveolar bone.According to the typical movement of teeth in the course of orthodontic, several simulated cases were designed and analyzed numerically.The dental cast's stress and strain with invisible orthodontic appliances were analyzed.And the comparative study was made between the invisible appliance and the traditional fixed aligner.Result Compared the invisible appliance with the traditional fixed aligner, the maximal stress on the dental cast and the changing tendency of stresses are greatly similar to each other.Conclusion The well orthodontics and satisfying the patient's needs for beauty during the course can be gained with the properly designed invisible appliance.