Abstract: Aiming at the problems such as impossible to restore the obstacle environment of the real production line of the robot arm path planning simulation experiment, insufficient authenticity of the algorithm simulation verification, tedious manual teaching operation of the production line in the workshop, and difficult real-time status monitoring of the robot arm, a digital twin-based path planning simulation analysis method of the robot arm was proposed. The construction method of the twin environment under the real production line of the robot arm was studied. OPC UA communication technology and Socket data transmission technology were adopted to open up the bidirectional transmission channel of the virtual and real robot arm operation data. The movement behavior of each moving part of the twin robot arm was determined according to the operation logic of the physical robot arm. The precise mapping of the motion process between the twin and the solid manipulator is realized. On this basis, the path planning method of dynamic elliptic constrained sampling RRT*-Connect manipulator is studied, and the grid collider in the twin environment is used for collision detection. Finally, Socket and OPC UA technologies were used to bind and update the control variables in the PLC and SDK, complete the updating of the teaching point of the robot arm, and carry out the operation monitoring of the physical robot arm based on the virtual and real synchronization technology. The feasibility and effectiveness of the proposed method were verified by taking the process of handling and clamping workpiece by a mechanical arm in a CNC machining workshop as an example, which provided a new simulation verification method for the path planning of the mechanical arm and improved the intelligent level of the production line in the workshop.