Normally, a man’s testicles are also one big and one small. The right testicle of a normal man will be slightly larger than the left testicle, and the difference is not too big. If the difference is too big, it may be due to congenital dysplasia or acquired lesions, it is recommended to go to the hospital to find out the specific causes before treatment. 1. Congenital dysplasia: If this happens at birth, it may be due to congenital dysplasia, and it is recommended to check the testicular function. 2. Acquired lesions: Testicular syringomyelia may cause the affected side of the testicle to become larger in size and the scrotum to become enlarged; orchitis or epididymitis may also cause the affected side of the testicle to become larger in size; varicocele may lead to testicular or scrotal shrinkage, resulting in atrophy of the testicle. Testicular size may also be caused by other factors, it is recommended that patients go to the regular hospital in time for treatment, and strive for a speedy recovery.