Objective To determine the effect of simulated ischemia/reperfusion (I/R) on the morphology and funny current(If) in sinoatrial node cells(SNCs) of newborn rabbits, and clarify the electrophysiological characteristic changes of SNCs after ischemia-reperfusion injury. Methods SNCs were isolated from newborn New Zealand rabbits by double enzyme hydrolysis/differential anchoring velocity, and then cultured under simulated ischemia reperfusion damage(95%N2＋5%CO2 for 1h followed by 95%O2＋5%CO2 for 3h). The cells cultured under normal condition(95%O2＋5%CO2) served as normal control. The morphological changes of the cells were observed under inverted microscope. Patch-clamp technique was used to record action potential and the If. Results Normal SNCs were mainly spindle in shape and smooth and complete in surface, with fast frequency of pulsation. While, the SNCs after simulated I/R injury showed swelling and distortion, with granular and unsmooth cell membrane and retraction of pseudopodia. After simulated reperfusion, the maximum diastolic potential of If in SNCs was changed from (-50.9±5.3)mV to (-43.5±4.6)mV, current density was changed from (-3.2±0.41)pA/pF to (-2.47±0.32)pA/pF, with its steady-state activation curve obvious to the right when compared with that of control, and the half activating voltage was changed from (-98.6±2.3)mV to (-107.8±4.7)mV (P＜0.05). Conclusion Simulated I/R induces injury in SNCs. Cell electrophysiological characteristics are changed, mainly in the If reconstruction.