Torsional fretting exists in many engineering applications and the contact configurations have great effects on the fretting wear behavior. Influence of angular displacement amplitudes and normal loads on torsional fretting were investigated under flat on flat contact. Friction torque versus angular displacement amplitudes and friction torque versus number of cycle curves were used to analyze the fretting kinetics behavior. Evolution of accumulated dissipated energy (ET) and wear volume (VW) with the change of angular displacement amplitudes were analyzed. The wear mechanisms were studied base on examinations under optical microscope (OM), scanning electron microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). It is found that ET and VW analysis helps to reveal the variation of failure mechanisms with the change of angular displacement amplitudes. Uneven spread of wear scar under mixed slip resulted from the effects of debris on stress-redistribution. Similar to ball on flat contact, the torsional fretting wear mechanism under flat on flat contact was a combination of deformation, cracks, delamination abrasive wear and oxidation wear.