A robot arm assembly includes a first shaft base, a second shaft base rotatably connected to the first shaft base, a wire harness, and a clamping mechanism for clamping the wire harness. The first shaft base defines a first through hole along a longitudinal axis, and the second shaft base defines a second through hole. The clamping mechanism includes a main body connected to the second shaft base, and a locking member engaged with the main body. The second shaft base rotates relative to the first shaft base around the longitudinal axis. The main body further comprise a clamping portion on an end thereof, and the clamping portion is capability of radial deformation. The locking member resists the clamping portion to clamp the wire harness. The wire harness extends through the first through hole, the second through hole, and then the clamping mechanism.