Echocardiography is a useful technique for diagnosing cardiovascular disease that is safe, reproducible and accurate. A comprehensive understanding of echocardiographic parameters in different age and sex is useful for cardiovascular study. Thirty Sprague-Dawley rats of both sexes at different age underwent repetitive echocardiography. The characteristics of early and late diastolic waves through the mitral inflow depend on the heart rate. The rats had fast heart rates, with early and late diastolic Doppler flows commonly fused. Several parameters in male rats were higher than in females except for ejection fraction, fractional shortening, isovolumetric relaxation time, pre-ejection fraction and ejection time that did not differ. Different age, sex, breed and anesthesia protocol can all cause diverse results. Rat echocardiography can be potentially used as a model for human cardiovascular research. Results revealed changes in echocardiographic parameters in different age and sex to better understand normal cardiovascular functions in rat model