The World Health Organization (WHO) recommends that if a couple has lived together for more than one year after marriage without using any contraception and the woman is infertile due to male factors, it is called male infertility. At present, there are about 60 to 80 million couples suffering from infertility worldwide, of which 50% are related to male factors. There are many causes of male infertility, mainly obstructive azoospermia, non-obstructive azoospermia and oligozoospermia. The testes are the “factories” that produce sperm, which need to pass through the epididymis, vas deferens, ejaculatory ducts, prostate and other sperm output tubes in order to be ejaculated out of the body. Problems in any part of the process can lead to male infertility. Diseases of the testes can lead to non-obstructive azoospermia or oligozoospermia, while disorders of any section of the vas deferens can result in sperm obstruction, leading to azoospermia. Defining the cause of infertility as well as correctly evaluating the spermatogenic function of the testes will help both the doctor and patient to choose the appropriate method of treatment for reproductive offspring. Male Reproductive System In patients with obstructive azoospermia, normal spermatozoa can be produced in the testes, but any part of the output ducts can be blocked due to lesions, resulting in the inability of sperm to exit the body. High-frequency combined transrectal ultrasound can visualize the patient’s epididymis, vas deferens, seminal vesicles, ejaculatory ducts, and prostate to make a definitive diagnosis of the location and cause of the obstruction in the vas deferens. Fertility can be achieved through microsurgery or assisted reproductive technology. Non-obstructive azoospermia is due to insufficient ability of the testes to produce spermatozoa and often manifests with small testicular size, soft texture and reduced blood supply. High-frequency ultrasound can accurately calculate testicular volume (normal 10~12 ml) and observe the distribution of texture within the testis; testicular hardness is assessed using elastography; and the hemodynamic status within the testis is assessed using color Doppler flow imaging (CDFI), and all three of which combine to provide high diagnostic value for the development of the testes and spermatogenic function. One of the causes of oligozoospermia is varicocele. Varicocele is caused by poor reflux and stagnation of blood flow in the spermatic veins, which increases the temperature of the testes. Ultrasound measures the degree of varicocele, hemodynamic status and other objective indicators, and is an effective component of screening for causes of male infertility. Sperm production and pathway Ultrasound is a preferred, non-invasive and reproducible imaging method for testicular and spermatogenic ducts examination, which has been widely quoted in clinical practice. The Department of Ultrasound Medicine of the hospital has accumulated rich clinical experience in male infertility ultrasound diagnostic techniques by analyzing, summarizing and studying ultrasound images of more than 5,000 cases of azoospermia.