Abstract: A digital twin model of the robotic arm based on the co-simulation of MATLAB and NX MCD is constructed with three degrees of freedom robotic arm. NX is used to build the 3D model of the robotic arm and give relevant motion drive parameters and constraints. Based on the Denavit-Hartenberg (D-H) kinematic equation of the robotic arm and the MATLAB platform, the PID control simulation system of the robotic arm is constructed, and the communication function of MATLAB and NX MCD co-simulation is further generated to realize the real-time interaction between the digital twin model of the robotic arm based on MATLAB and the NX platform. Through the simulation of the virtual model of the robotic arm in this paper, it is found that the error between the control signal parameters of the co-simulation and the execution parameters of the NX MCD virtual model is within 0.5%, which realizes the motion simulation of the twin model with high fidelity, high accuracy and high efficiency, and provides a theoretical and practical basis for the research of the digital twin model of the robotic arm and other complex mechanical systems.