Abstract: When the three-jaw chuck is used to turn the cross shaft, multi-pass pipe joint and other types of parts, the corresponding work fixture should be designed to each end of the turning, which needs multiple clamping and is difficult to ensure the machining accuracy, leading to time consuming and laborious. Therefore, a new hydraulic dividing chuck is designed and introduced in this paper, which has implemented the function, after finishing one end of the machining, the rotating shaft can be partially rotated for machining the lower end. Meanwhile, the overall structure of chuck body and hydraulic system is designed, and the PMC ladder diagram of chuck is perfected according to the control flow of FANUC NC system, achieving automatic operation of chuck action.