Theoretical analysis and practice experience has shown that, the vibration signal on power transformer surface can be used to analyze and judge the work state of the winding and iron core. For vibration analysis, to extract a precise feature of the vibration signal is a basic work. Three-dimensional surface vibration signal of the running power transformer is analyzed based on wavelet multiresolution analysis. Based on the Parseval theorem, the feature of frequency bands-energy in X, Y, Z directions is computed and compared. It can provide some reference for the power transformer vibration analysis.