Objective To explore the rule of voltage change in the reference point of electrocardiograms(ECG). Methods The r and R′ waves on the head-chest lead and routine lead ECGs in 21 patients with right bundle branch block in whole synchronization were compared, and the correlation of voltage change in reference point with the direction of cardiac muscular stimulation of ECGs was analyzed.Results The swing of wave r in head-chest leads was significantly higher than that of routine leads(\[0.16±0.19\] vs \[0.11±0.13\] mV, P<0.01), and the swing of wave R′ in head-chest leads was significantly lower than that of the routine leads( \[0.25±0.21\] vs \[0.35±0.23\] mV, P<0.01). Conclusion Voltage change in reference point of ECG varies with the direction of cardiac muscular stimulation.