The present invention provides an osmotic orthodontic appliance, comprising: an actuation structure forming a hollow tube filled with a supersaturated solution; a dental aligner structure mounted on the actuation structure for fixing the actuation structure on teeth; and a pumping structure connected one end of the hollow tube, comprising a semipermeable device and a supporting structure. The osmotic orthodontic appliance of the present invention could provide steady movement and force output; it is a solution for the periodic actuation problem of conventional orthodontic appliances.