Abstract: When a robot operates at high speed,the deflection of its end-effector due to joint elasticity will affect the tracking precision of the robot.Redundant robots with elastic joints are considered study objects in this paper. The effects of redundancy resolution on joint elastic deflection of robots are researched. First,a redundancy resolution method called constant weight factor method is proposed by using joint elastic deflection as a performance index. And then based on this method,two improved methods, variable weight factor method and exchange method ,are presented further.The former uses a variable weight factor to automatically adjust angular acceleration′s influence on general objective function; the latter uses a threshold function to realize the exchange between two different resolution methods. At the same time, a necessary condition for the two improved methods to obtain optimal solutions is also given.Finally, a planar 3R redundant robot is used to make a simulation research, and comparisons among the three methods are also made .Study results show that the two improved methods have a good global characteristic.