Abstract: Objective: To evaluate the effect and the regularity of time-related change of class Ⅲ intermaxillary orthopedic force loading on the maxilla of puberty rhesus. Methods: The animal model was established with 6 puberty female rhesus, which were randomly divided into experimental group(wore class Ⅲ twin-block magnet appliance, each 2 rhesus for 3 and 6 month respectively) and control group(did not wear any appliance, each 1 rhesus for 3 and 6 month respectively ). The lateral radiograph was taken monthly and computer-aided system was used for lateral cephalometry. Results:(1)Compare to the control group, the occlusion of experimental group were changed obviously;(2)Cephalometric measurement showed that normal forward and downward development was observed in control group and maxilla moved forward and slight clockwise rotation was observed in experimental group;(3)The spatial change of maxillary was occurred in the first two month, but the maximum value of length was achieved at the third month;(4)There was a limit exist in the reaction of the maxilla to orthopedic force, additional loading can not promote more spatial change or length increase. Conclusions: Class Ⅲ orthopedic force can obviously change the spatial position and length of maxilla and the former occurs earlier.