Infants with one large testicle and one small testicle can be considered to be related to hernia, spermatic cord syringomyelia or cryptorchidism. 1. Hernia: Hernia occurs more often in infants, in the inguinal region of congenital defects, abdominal dysplasia, etc., can be induced by constipation, crying and other factors, hernia can be protruded into the scrotum through the inguinal canal, thus making the affected side of the scrotum larger, the scrotum can be seen as a large and a small scrotum. 2. Syringomyelia: If congenital traffic syringomyelia occurs, because the sheath protrusion is not closed, the fluid in the syringomyelia sac can be connected with the abdominal cavity, which can make the scrotum appear lumpy and gradually increase in size, and there is a feeling of dropping and pulling of the scrotum when there is a lot of fluid accumulation, so the testicles are seen to be of different sizes. 3. Cryptorchidism: at this time, the testicle can be located above the inner ring of the inguinal canal or even located in the retroperitoneum, which is caused by incomplete descent of the testicle, and the testicle on the affected side can not be touched or seen, and it can lead to a large testicle and a small testicle. When you find that the size of scrotum is different, parents are advised to bring their children to the doctor in time, and after a clear diagnosis, targeted treatment will be carried out.