Objective To analyze the electrocardiography (ECG) data of pressure overload-induced chronic heart failure rats.Methods Totally 20 SD rats were randomly divided into sham operation group and heart failure group. Heart failure rats were induced by abdominal aorta constriction.Echocardiogram measurement demonstrated the occurrence of cardiac function.Two lead ECG parameters of limb a was measured and statistically analyzed.Results Ten weeks after operation, there was a increase in heart rate, P amplitude, P duration and R amplitude comparing by those of the sham operation group (P<0.05). ECG showed a significant and ubiquitous J point elevation (P<0.05), with ST segment notable depression (P<0.05).Conclusions ECG in pressure-overload chronicity heart failure rats exhibits obviously characteristic features. ECG is an useful tool for objective and accurate assessment of cardiac function in rats.