Abstract:to investigate the anti-arrhythmia mechanism of Wenxin Granule by studying its effects on electrophysiological characteristics of adventitia and endomembrane in rabbit.Methods:capillary glass microelectrode was used for recording change of TAP parameters under different stimulation frequency.Results:(1) the granule could prolong action potential duration(APD). When basic cycle length (BCL)reached 1000ms, APD90 of endomembrane rose to (243±8)ms from (216±15)ms(P<0.01), adventitia APD90 were up at (228±10)ms from (182±11)ms. (2) the granule could remarkably cut down TDR. When BCL reached 1000ms, TDR was (21±10)ms from (33±9)ms(P<0.01).Conclusion:Buchang Granule can prolong APD of adventitia and endomembrane and reduce TDR of aortic ventricle of heart.