Abstract: Spatiotemporal gait parameters provide important information for the rehabilitation of patients with gait dysfunction. These parameters are often obtained by complex systems such as optical motioncapture system and pressure plates. However, these systems cannot be deployed at the lower-limb rehabilitation robot easily because of high costs, large area occupation and wearable requirements. We present a gait measurement system with a Light Detection And Ranging(LIDAR) laser sensor based on the lower-limb rehabilitation robot. Firstly, to calculate gait parameters, the data are aggregated into left and right legs by the clustering algorithm and the legs contour is fitted with two circles respectively according to the least square method. Then, the spatiotemporal gait parameters are defined based on the time and position of initial contact(IC) and toe off(TO). Finally, to verify the validity of the proposed system, we compared the results of the proposed system with a 3D motion capture system based on a lower-limb rehabilitation robot. Experimental results showed that the gait detection system can measure the parameters within a small range of error that testified the validation of the proposed system. This system proved to be a valid and reliable method for the measurement of gait parameters.