To explore the effect of jianxin pinglu pill (JPP) on arrhythmia and aquaporin 4 (AQP4) in rats with myocardial ischemia/reperfusion (I/R) injury. The effects of JPP on arrhythmia, mortality and AQP4 on I/R injured rats model induced by blocking left coronary artery were observed using II lead of ECG, HE stain and AQP4 immunohistochemical stain. JPP showed significant effect in lowering the arrhythmia occurrence and mortality, reducing myocardial ischemic edema and injury, strengthening AQP4 expression in myocardial tissue. JPP has the effect of preventing I/R induced arrhythmia, it might be related with its action in up-regulating AQP4 expression level in myocardium and reducing the intracellular edema.