In the process of ultrasonic nondestructive testing in the industry, due to environmental reasons, from instrument noise, form a certain interference to the subsequent defect analysis, is not conducive to the completion of data analysis. In order to improve the signaltonoise ratio, the signal waveform closer to no noise, proposes an improved empirical mode decomposition the threshold denoising algorithm. Compared with wavelet soft threshold denoising method and EMD method to eliminate the repetition interval of the threshold, the establishment of mathematical model of ultrasonic echo in MATLAB simulation software and the algorithm is verified. The experimental results show that the EMD denoising method is better than wavelet threshold denoising, the improved empirical mode decomposition threshold denoising method based on SNR, mean square error, smoothness are the three aspects to improve, achieve better noise reduction effect.