Abstract: A face-on-face torsional frictional tester has been developed for measuring face-on-face torsional frictional property. The sliding and torsional frictional experiments of glass fiber reinforced monomer casting nylon (MC nylon) against 45^# steel were performed under a normal load of 123 N, angular displacement amplitude of 60°and 90°. The wear surface morphologies of MC nylon composite were observed with a scanning electron microscope (SEM). The transfer films morphologies of 45^# steel were observed with a microscope. Experimental results indicated that, under torsional condition, the torsional torque increased with increasing running cycles, while the T-θ curves remain parallelogram curves. Friction coefficient under torsional condition was higher than that under sliding condition. The mass of MC nylon samples increased after torsional wear. The wear mechanism under torsional condition showed more severe adhesive wear and fatigue wear than that under sliding condition. Under sliding condition, continuous transfer film with large area formed on the surface of 45^# steel plate, but under torsional condition, there were a few strips of transfer film in the center of contact region of the 45^# steel plate.