The reliability of kinematic trajectory of manipulators describes the ability that manipulators keep kinematic accurate. It is an important parameter to evaluate the performance of manipulators. The kinematic accuracy of manipulators can be improved when piezoelectricity material are used as a transducer to suppress the vibration of flexible manipulators. First, a 3 degree-of-freedom parallel manipulator system and its dynamic equations are introduced. The theory and experiment of a vibration suppression system are then presented. The calculation method of both error and reliability of kinematic trajectory of manipulator is further implemented. Finally, the reliability of kinematic accuracy are calculated and analyzed for the 3 degree-of-freedom parallel manipulator with or without vibration suppressing control. The results show that the reliability of kinematic accuracy is improved using vibration suppressing control.