The invention discloses a robot arm part, which comprises a first shaft body, a second shaft body rotationally connected with the first shaft body, a first driving piece, a first transmission mechanism, a second driving piece and a second transmission mechanism, wherein the first driving piece drives the second shaft body to rotate around a first axis relative to the first shaft body through the first transmission mechanism; the second transmission mechanism comprises a first gear driven by the second driving piece and a second gear meshed with the first gear; the second shaft body has a second axis and an output shaft; the output shaft can rotate around the second axis, and is fixedly arranged on the second gear; and the second shaft body, the output shaft and the second gear are provided with wire holes taking the second axis as an axis. The robot arm part can prevent cables from winding the second shaft to avoid abrasion.