Dealt with in this paper are the effects of singularity configuration and servo gain of drive motors on the self-excited vibration of planar 3-RRR parallel manipulator.Firstly,the kinematics constraint equation of the planar 3-RRR parallel manipulator was established,and the velocity constraint equation as well as the acceleration constraint equation was obtained via derivation.Meanwhile,the forward and inverse solutions of position,velocity and acceleration are analyzed.Secondly,the singularity was measured by using the velocity Jacobin matrix.Then,an experimental system was established to test the self-excited vibration respectively in singular and non-singular configurations after analyzing the control principle of drive motors.Moreover,the input position,velocity and acceleration of active joints were tested by sensors,the position and acceleration of the moving platform were obtained via forward kinematics,and the obtained acceleration of the moving platform accord with the test one well.Finally,the self-excited vibration in non-singular configurations was successfully avoided by adjusting the servo gain of drive motors.