Ovarian cysts are an important cause of infertility and can be divided into follicular cysts and corpus luteum cysts. It is necessary to distinguish between the two to determine the treatment. Veterinary B ultrasound imaging is a good means of distinguishing. Ultrasound imaging shows that follicular cyst is a uniform non-reflective structure with a diameter greater than 25 mm and a membrane thickness less than 3 mm. The non-reflective structure of the corpus luteum cyst is larger than 25 mm in diameter, with gray spots in the corpus luteum or along the intima, and the membrane thickness is greater than 3 mm. At the same time, attention should be paid to distinguish between the corpus luteum cyst and the luminal corpus luteum, which is non-pathological. The two can be distinguished by size, cavity shape, film thickness and internal area reflection characteristics. Usually, the cavity corpus luteum is less than 3mm, the film thickness is about 5-10mm, the shape is oval, the cavity shape is round or oval, and the liquid-filled cavity is uniform and almost no reflection. The corpus luteum cyst is often seen with reflexes.