Abstract: Modern roobt needs the characteristics of moving rapidly, grasping heavier weight, giving better accuracy and providing better manipulability. The structure flexibility of robot arm results in the hard to controlling robot arm with high accuracy and high speed. For getting over the defaults of non redundant robot arm, to study the flexible redundant robot is neccessary. In this field, neither in world nor in our country, published few paper. In this article, we give a method of using the self motion of redundant robot to conquerd the fault of vibration that results from the nature of flexible structure of robot arm. From theory, we analysis the fundamental of the given method, and finally, using the space four degrees robot that was designed by us to simulate the simulation results verifies the method is valid to be used to suppress the vibration of robot arm end point.