Objective To explore the influence of ultimate activity on the stabilization of Scaphotrapeziotrapezoid (STT)arthrodesis. Method 6 fresh cadaver fore-arm were used to make scapholunatum dissociation (SLD) and STTarthrodesis before ultimate activity (50,000 times/per 5°) simulation. Anterior-posterior view and lateral view were takeneach time before and after the motion. Radialoscaphoid angle(RSA)、radialoscaphoid interval (RSI) and length ofscaphoid were measured and the cinch、bent of the Kirschner Wire were recorded as well. All of the wrists werecompared by self-control in the test. Result Comparing with the control groups, the difference of RSA、RSI、lengthof scaphoid and Bent positive ratio of Kirschner Wire showed statistical significance withthe flexion、extenion、radialand deviation beyond 55°, 40° and 10°, respectively (P<0.05). But, the index mentioned above showed no statisticalsignificance (P>0.05) during whole process of the ulnar deviation. Conclusion It is safe for the wrist within the rangeof motion not beyond flexion 55°、extenion 40°、radial deviation 10°, but circumduction should be avoided.