EMG interference is the noise interference caused by slight muscle vibration in the process of ECG acquisition,so it is necessary to de-noise the acquired ECG signal further.Aiming at the problem of Oscillation and distortion of ECG signal after de-noising by traditional wavelet threshold, an improved wavelet threshold function with two dynamic parameters is proposed,the improved threshold function can be adjusted in whole and in part by the dynamic parameters, so that the noise can be denoised in different degree.In order to verify the de-noising effect of the new threshold function, the signal-to-noise ratio (SNR) , mean square deviation (MSE) and the time-frequency characteristics of ECG were used to evaluate the de-noising effect, the improved threshold function is compared with the traditional EMG denoising algorithm.The results show that the improved threshold function can preserve the characteristic waveform of ECG signal after de-noising, and overcome the shortcomings of soft and hard threshold function.Compared with the traditional EMG interference denoising algorithm, the signal-to-noise ratio of denoising slight noise and serious noise is 38.7948 and 36.7212 respectively, and the mean square deviation is 0.0013 and 0.0018 respectively,the denoising evaluation result is the best.