Outofroundness (OOR) wear tests on two chosen locomotives were conducted,one of them suffered frequent alarms while the other operated normally.The OOR wear wear characteristics of normal and abnormal vibration alarm wheels were compared and analyzed.The test results show that loworder OOR wear is the primary abrasion pattern of normaloperated locomotive wheels.However,the wheels experienced frequent occurrence of abnormal vibration contains obvious OOR wear from 16 to 25th order in addition,which is the main root of abnormal vibration of locomotives.The locomotive/ballast track coupled model was established,the effect of OOR wear on the dynamic interactions of wheel/rail system was investigated,and the variation of dynamic response of wheel/rail with respect to the basic feature of polygonal wear was studied systematically.The research results indicate that the impact between wheel and rail will intensify under excitation of severe OOR wear,the dynamic response is increased with the increase of wear amplitude,but presents a nonlinear trend with the increase of wear order.