ECG plays an important role in the diagnosis of arrhythmia, but ECG signal is easily disturbed by various noises, which will change the shape of the signal and affect the accurate diagnosis of arrhythmia.This paper proposed an improved empirical wavelet transform denoising algorithm of ecg signals, divide the spectrum according to the frequency domain characteristics of ecg signal, and get rid of the noise by calculating the zero rate and the correlation coefficient of empirical mode functions, use wavelet threshold method to remove the residual noise. The experimental results show that the baseline drift and EMG interference are effectively filtered. SNR of the denoised signal is 17.7382db and RMSE is 0.0203, which is better than other common methods. The improved empirical wavelet transform algorithm has obvious noise reduction effect and can effectively restore the original ECG signal features.