Electrocardiogram (ECG) signals are susceptible to be disturbed by 50 Hz power frequency in the process of acquisition and conversion. This paper puts forward the improved Levkov algorithm combined with the antisymmetry of sine wave and the characteristic of not-easily mutation of the sine wave amplitude. The improved and the original algorithms were compared with signal to noise ratio (SNR), root mean square error (RMSE) and coincidence of the signals. Based on the experimental comparison, it was concluded that the improved algorithm had better filtering functions, because it not only highly coincided with ECG, but also retained certain details of ECG.