Abstract: A method to identify the dynamic model parameters of modular robot with flexible joint using 3D motion measurement system Optotrak3020 is proposed.Firstly,the robot dynamics model is parameterized in a linear form to exclude the stiffness torque and the scaling problem is eliminated from the parameter matrix.The exciting trajectory is based on the finite Fourier series function and the coefficients of the Fourier series are optimized with the self-adaptive genetic algorithm.When each joint of robot is commanded to follow the single-joint optimized exciting trajectory,the motor position,link position and motor torque are measured and recorded in real time.Finally,using the classic linear least square parameter identification,the dynamic parameter identification experiment is carried out on the first three joints of PowerCube modular robot,and parameters of robot dynamic model are derived.