Abstract: To improve the tracking accuracy of the gait trajectory of the lower limb exoskeleton robot (LLER) , an experimental method of parameter identification is proposed for the LLER’s two-link dynamic model, including static and dynamic experiment. Combined with the wearer’s human parameters, the accurate dynamic model of the LLER human-machine collaborative system is deduced. The sliding mode control (SMC) with the upper bound of the model and a low-pass filter are adopted to track the gait trajectory precisely by MATLAB. The simulation shows that the waveforms of the hip and knee torques measured by experiment are basically consistent with the theoretical values by calculation, and the dynamic parameter identification results are correct. The human-machine collaborative system based on SMC can realize the accurate tracking of the reference gait trajectories of the hip and knee joints, and the low-pass filter can effectively reduce the high-frequency chattering caused by SMC. This research provides a solution for the identification of the dynamic parameters of LLER, a reference model for the model-based control method, and a reference method for precisely tracking the gait trajectory of LLER human-machine collaborative system