A number of commonly used transformer inrush current recognition methods are analysed to compare the wave and half-wave difference Fourier algorithms for inrush current calculations. A recognition method for transformer inrush current is proposed. This method is based on combination of fluctuation error and peak-to-peak space method. This method is simple in calculating and impregnable of initial time. This method reflects the essential characters of inrush current， and is easy to set. Simulation results illustrated the effectiveness of the proposed transformer inrush current detection method.