The utility model provides a high-safety high-precision joint of a medical mechanical arm, which relates to the technical field of medical robots and comprises an input shaft, two RV speed reducers and a
servo motor, the axis of the input shaft is horizontally arranged, and the two RV speed reducers are symmetrically mounted at two ends of the input shaft and coaxially arranged with the input shaft. The two ends of the input shaft penetrate through middle holes of the two RV speed reducers and are in gear meshing transmission with
planet wheels of the two RV speed reducers, the fixed ends of the two RV speed reducers are away from each other and connected with the rotating arm, and the output ends of the two RV speed reducers are close to each other and connected with the pitching arm. The
servo motor is arranged on the
peripheral sides of the two RV speed reducers and arranged in the pitching arm, an output shaft of the
servo motor is parallel to the input shaft, a transmission
assembly is arranged between the output shaft and the input shaft, and
brake assemblies are arranged on the servo motor, the transmission
assembly, the input shaft and the input ends, away from the transmission
assembly, of the RV speed reducers. The
brake device has the advantages of being large in load, high in rigidity, small in size, compact in structure, low in
noise and the like, high safety and closed-
loop control are achieved through the multiple
brake assemblies, and the joint control precision is improved.