It is not normal to have one large testicle and one small testicle. A normal male adult usually has two testicles, both of which are located in the scrotum and are generally similar in size. If the testicles are one big and one small, it is usually due to the presence of lesions in the scrotum, such as the common testicular syringomyelia, which increases the syringomyelia surrounding the testicles, resulting in a significant increase in the testicles when they are touched. In addition, there is another reason for the presence of swelling in the testicles, at this time it is necessary to go to the hospital as soon as possible to do a detailed examination, a clear diagnosis to find out the specific cause of the disease, in order to take different treatment methods according to the cause. If it is due to an increase in testicular sphingomyelia, it can be treated through surgery. If it is due to a testicular mass, it needs to be treated through surgery according to the nature of the tumor, and it can also be treated through radiotherapy and chemotherapy. If you have undergone surgery, you should try to avoid excessive physical labor and avoid sexual intercourse for 6 weeks after the surgery to avoid infection.