Objective：To study the changes and rules of the reference point potentials of electrocardiograms (ECGs) before and after pacing. Methods: The head-chest lead and routine lead ECGs of the patients with permanent pacemaker implantation were recorded with and without right ventricular pacing; the Q, R and S wave amplitudes were compared between the 2 ECGs.Results: Without right ventricular pacing, the amplitudes of Q and S wave of routine lead were higher than those of the head-chest lead; the amplitude of R wave was lower than that of the head-chest lead. With right ventricle pacing, the amplitudes of Q, R, and S waves of routine lead were lower than those of head-chest lead(all P<0.01).Conclusion: The transduction direction of the cardiac excitement has great influence on the potentials of the reference point.