In this paper,an EMD (Empirical Mode Decomposition) algorithm based on wavelet packet transform is proposed and applied to ultrasonic echo signal de-noising.For the problem of mode mixing caused by the EMD decomposition of ultrasonic flaw signals with Gauss white noise,wavelet packet transform is applied to preprocess ultrasonic echo signal,and followed by EMD decomposition,finally the useful defect signal is reconstructed.The experimental results show that,this method has good de-noising effect with small waveform distortion of reconstruction defect signal.It is conducive to the further quantitative analysis of ultrasonic echo signal.