Abstract: Low-velocity friction torque characteristics of proportional valve-controlled hydraulic motors are studied by experiment.Low-velocity friction torque characteristics of hydraulic motors are analyzed based on the steady-state experimental curves of proportional valve-controlled hydraulic motor.Experimental devices to measure low-velocity friction torque were designed,and the experimental method and procedure described.The low-velocity friction torque characteristics have been tested under different oil temperatures and load torques,and the low-velocity friction torque model is obtained from the test data.The study results showed that the low-velocity friction torque of the hydraulic motor has severe nonlinearities,and the oil temperature and load torque variations have a marked effect on it.The low-velocity friction torque model proposed in this paper conformed well to the experimental results.