The testicles are a unique male reproductive organ that secretes androgens and produces sperm. They are located in the scrotum, one on each side, and play an important role in male fertility and sexual function. The testicles of some people will have a large and a small, or a high and a low, if the difference is not large is normal, no special treatment is needed. If there is a big difference in testicular size and painful symptoms, it is necessary to consider certain diseases, such as orchitis, epididymitis, testicular syringomyelia, testicular tumor, testicular atrophy, etc. If it is caused by orchitis or epididymitis, it is often accompanied by testicular pain and scrotal redness and swelling, so timely anti-inflammatory treatment is needed. If the testicular enlargement is caused by testicular sphingomyelia, surgical treatment or puncture and fluid extraction treatment is required depending on the case. If the testicular tumor is caused by the testicular tumor, then timely surgery is needed, and after surgery, according to the pathological results of the corresponding radiotherapy or chemotherapy. To sum up, if the difference between one testicle and one small one is not big and there are no uncomfortable symptoms, no special treatment is needed and most of them are normal. If the difference in size is large and accompanied by pain and other uncomfortable symptoms, it is necessary to make a clear diagnosis and then do targeted treatment.