Objective To study the effect of lactate of differentconcentration on the action potential of ventricular papillary muscle cell (n=4) and contractile force (n=10).Method Using intracellular microelectrode technique and microtension depicting method.Result The Result showed the effect of lactated solution of a certain comcentration became obvious. After perfused with lactate solution of 4mmol/L,the vilocity maximum decreased significantly (p<0.05) showed the 4mmol/L lactate solution decreased the rate of depolarization: decreased the efficency of Na + channel; lactate solution decreased the contractile force of cardiac muscle. Conclusion The possible mechanism was: Ca+ influx and Na+ - H+ exchange were inhibited, resulted in the elevation of intracellular H+ concentration; through Na+-Ca2+ exchange, Ca2+ efflux decreased resulted in the intracellular Ca2+ decreased resulted in the intracellular Ca2+ overload.