Abstract: In order to assist the surgeon to accomplish micro-surgery better,we develop a new master-slave isomerous micro-surgery robotic system,i.e."MicroHand".The master manipulator is Phantom Desktop,which is a commercial robot with comfortable manipulability.The slave manipulator is developed by our lab,which is designed for the micro-surgery.The slave manipulator includes two parts: position mechanism and orientation mechanism.The position mechanism can implement kinematic characteristics of double four-bar linkage structure by cable driving,and the orientation mechanism applies the structure of three rotating axes intersecting at one point.Based on the kinematic analysis of the double four-bar linkage mechanism and the kinematic conditioning index,we optimize the double four-bar linkage mechanism.The result indicates that the system has the maximal dexterity when the first three links of the double four-bar linkage mechanism have equal length and link I is perpendicular to link III.