A ballonring friction measuring system was designed,which can simulate the contact between the rolling element and the outer ring of the rolling bearing,and by adjusting the rotation speed of the ball and ring,the friction under different slideroll ratios can be measured.The composition and measurement principle of the system were introduced,and two base oils,PAO20 and PAO40,were used for measurement experiments to verify the accuracy of the system.The curves of friction coefficients under different slideroll ratios,entrainment speed and load conditions were measured by using this system.The results show that the friction coefficient increases slowly until flat with the increase of the slideroll ratios,and the friction coefficient decreases gradually with the increase of the entrainment speed.The results are consistent with the classical lubrication theory,which verifies the accuracy of the measuring device.