Abstract: Detection for hidden defectsof aluminum alloy plate with damping coatingofrailway vehicles is interfered by stiffener, so the position of stiffener is necessary to be locateed. The remote field eddy current detection model of aluminum alloy plate with damping coating,optimizing is stablished tand the optimal excitation frequency for the positioning stiffener is analyzed; According to the relationship between the width h of the stiffener and the outer diameter D of the excitation coil, the characteristics of the detection signal characteristics of H<D, H=D and H>D are studied. The remote field eddy current detection test platform is set up and the platestiffener positioning test was carried out. The test results show that When the excitation frequency is 0.6 kHz and thick non-conductive layer is 5 mm, this positioning method can complete the location detection of aluminum alloy floor reinforcement with a width of 3 mm. The test results are consistent with the simulation results. The far-field eddy current detection technology can effectively solve the location detection of high-speed EMUs’ aluminum alloy plate with dampingcoating.