The acoustic vibration signal of tank is disassembled into the sum of intrinsic mode function (IMF) by multi-resolution empirical mode decomposition (EMD) method.The instantaneous frequency is obtained,and feature transformation matrix is figured out by class scatter matrix.Multidimensional scale energy vector is mapped into low-dimensional eigenvector,and classification extraction is realized.This method sufficiently separates of different sound target features.The test result indicates that it is effective.