Abstract: A novel fault diagnosis approach for robot manipulator is proposed,which constructs residuals of multi-joint virtual links through rotational transferring relation between joints. So the redundancy relation between manipulator workspace residual and visual link residuals can be used as the criterion of fault diagnosis. This approach overcomes the shortage of the existing method which does not utilize the space relations among joints by designing a threshold of residual associated with manipulator end trajectory excursion from desired track.