In order to solve the problem of ECG acquisition and processing better, this paper designs a portable ECG tester, which uses the SCM as the core controller. Power basic frequency interference was removed by 50 Hz trap filter. Power harmonic interference, electrode polarization interference and my electricity interference were removed by low- pass filter. Baseline drift was removed by high- pass filter. At the same time; we test the performance of acquisition circuit, filter circuit and amplification circuit. As a result, it is shown that the system can well collect and process ECG signal.