With the development of assisted reproductive technology and the ethical limitations of research on humans, rat animal models have been widely used in reproductive medicine. In the past, the study of reproductive system development in rodents has been based on one-time histological examination of excised tissues. Recently, with the development of high-resolution transabdominal ultrasound, high-quality sonography can now be performed to evaluate the reproductive organs of rats, allowing a new method for studying the reproductive system. Images were obtained using a high-resolution ultrasonographic system. Gynecological ultrasonography was performed on 28 eight-week-old non-pregnant rats and 5 pregnant Sprague-Dawley rats. We describe how to recognize organs of the reproductive system and associated structures in typical views during different phases of the estrus cycle. Color flow Doppler was used to measure uterine artery blood flow and evaluate uterine blood flow pattern changes during different stages of pregnancy. We have demonstrated that ultrasound exploration is a useful method for evaluating changes in internal reproductive organs. Its use raises the possibility of conducting additional experiments, including medical or surgical procedures, and provides the ability to monitor sonographic changes to internal organs without sacrificing animals.