Abstract: The development status and existing problems of the joint locking mechanism of minimally invasive surgery robot guided by computerized tomography(CT) are analyzed.The principle of robot joint friction torque and the in?uence factors on friction torque are discussed.According to the deficiencies existed in the locking structure of current medical robot,three locking structures of minimally invasive surgery robot with CT navigation are presented based on joint friction theory,and their working principles and realization forms are expatiated respectively.Experiments are made on different structures to compare their performance,and the locking structure of robot joint with exterior friction ring is determined.It is validated that robot system with the presented structure can meet the requirements of clinical operation for minimally invasive surgery with CT navigation.