Abstract: AIM:To analyze the parameters of normal fetal chamber size and blood flow at different gestational weeks and to provide a reference standard for the examination of fetal echocardiogram. METHODS: A cohort of 1182 normal fetuses was divided into five groups according to different gestational weeks. The inner diameters of cardiac chambers and great vessels and the peak blood flow velocity of each valve orifice were measured by abdominal ultrasound and the parameters were analyzed statistically. RESULTS: The right chambers were larger than the left chambers (P<005) and the inner diameter of the pulmonary artery was bigger than that of the aorta. The peak blood flow velocity of the tricuspid valve was higher than that of the mitral valve (P<005). The blood flow Epeak velocity of mitral valve and tricuspid valve were both lower than the Apeak velocity (P<005) and the peak blood flow velocity of the aortic valve was higher than the pulmonary valve (P<005). CONCLUSION: Echocardiography can be used in evaluation of normal fetal chamber size and blood flow, which is very important for identification and diagnosis of fetal cardiovascular abnormalities.