The invention designs a knuckle movement module of a five-finger dextrous hand based on the structural features and kinetic characteristics of a worm wheel and worm mechanism. Movement functions of all fingers are satisfied, additionally, the space structure of knuckles can be optimized to the maximum, the used worm wheel and worm mechanism has a self-locking function, and therefore, the designed knuckle movement module of the five-finger dextrous hand can achieve the poweroff self-locking function, so that the grasping ability of the dextrous hand is increased, and the movement and grasping requirements of the five-finger dextrous hand are satisfied. A worm wheel and worm speed reducer which is used as a driving unit of the knuckle module is mainly composed of a worm wheel, a worm, a gear, a shaft, a bearing, a box body and accessories and can be divided into three basic structures including the box body, a worm wheel and worm gear set and the combination of the bearing and the shaft, wherein the box body is a base of all parts in the worm wheel and worm mechanism and is an important part for supporting and fixing shaft components, guaranteeing correct positions of all transmission parts and supporting loads which act on the speed reducer; the worm wheel and worm gear set is used for transferring output power of a motor and changing the direction of the output power; the combination of the bearing and the shaft is mainly used for transferring power, supporting operation and improving the efficiency.