The invention discloses a precision polish-grinding robot system for bathroom metal parts. A belt sander motor, an upper sliding block, a lower sliding block and a tensile force adjusting device are all installed on a main supporting plate. The upper sliding block is connected with an upper guide rail in a sliding mode. The lower sliding block is connected with a lower guide rail in a sliding mode. Both the upper guide rail and the lower guide rail are installed on a belt sander support. A driven belt wheel and a driving belt wheel are arranged up and down in parallel. A sanding belt is wound on a driving shaft of the belt sander motor, the driving belt wheel, the driven belt wheel and the tensile force adjusting device. One end of a position adjusting device is fixedly arranged on the main supporting plate, and the other end of the position adjusting device is fixedly arranged on the belt sander support. A robot control cabinet and an industrial robot are both installed on a robot pedestal. A six-dimensional force sensor assembly is installed on the head portion of the industrial robot. A clamp is installed on the six-dimensional force sensor assembly. A robot holding device is arranged in front of the driven belt wheel and the driving belt wheel of a belt sander. The precision polish-grinding robot system is used for polish-grinding of the bathroom metal parts.