Objective There are many interferences such as power interference, electrode polarization interference, myoelectricity interference, baseline drift, apparatus buzz and so on in electrocardiosignal acquisition system. It is very difficult to effectively remove these interferences in the process of actual measurement. Methods Power harmonic interference, electrode polarization interference and myoelectricity interference were removed by low-pass filter. Baseline drift was removed by high-pass filter. Power basic frequency interference was removed by 50 Hz trap filter. Results These three design proposals had such advantages as good effect, rapid speed and easy realization. Conclusion They can be well applied in ECG monitor with embedded CPU and real time character. Besides, they can also be used in medical apparatus measuring other biological electric signals and industrial observation and control system.