Mumps is an acute infectious disease caused by the mumps virus, which causes diffuse swelling of the parotid gland around the earlobe, commonly known as “mumps”. The mumps virus is highly contagious and can occur throughout the year, more often in winter and spring, and is easily prevalent in kindergartens and elementary schools. The main route of infection is through droplets from sneezing and coughing, followed by food and utensils contaminated by virus-carrying saliva. The virus enters the body and mainly attacks the glands: parotid, submandibular, sublingual and other salivary glands, gonads, pancreas, thyroid and lacrimal glands, while other organs such as the brain, meninges, heart muscle, liver and kidneys can be affected. Many men with infertility can often trace their history of mumps back to childhood. When the mumps virus attacks the testicles, it can cause inflammation of the testicles, which can manifest itself as swelling and pain in the testicles, accompanied by systemic symptoms such as fever, chills, nausea, and vomiting. The mumps virus causes atrophy of the testicular tissue and destruction of the seminiferous tubules. If both testes are destroyed by the virus, it can cause lifelong infertility and is difficult to cure. The diagnosis of orchitis is not difficult to establish, with symptoms such as testicular pain and discomfort, swelling of the testicles unilaterally or bilaterally, with pain often radiating to the groin, along with signs and symptoms of mumps. Sometimes inflammation occurs on only one side, but degenerative lesions may still occur in both testes, manifesting as testicular atrophy. If atrophy occurs in one testicle, it will have less impact on fertility and will not affect sexual life after marriage; if both testicles are involved, it is likely to lead to sterility, and if atrophy of the fine ducts of the testicular flexure still occurs fertility will be seriously affected. In severe cases, testicular biopsy reveals that no spermatogenic cells exist in the patient’s varicocele, and there is no hope for the recovery of fertility in such patients.