Large testicles in toddlers may be caused by testicular syringomyelia, orchitis, inguinal hernia and so on. 1. Testicular syringomyelia: If the syringomyelia of a toddler is not closed, the fluid in the abdominal cavity will flow to the syringomyelia sac to form syringomyelia, which will make the fluid around the testicles, and make the testicles appear swollen. 2. Testiculitis: the immunity of young children is relatively low, if the urinary system is infected, it is likely to lead to infection of the reproductive system, thus causing testicular inflammation. Or when a child suffers from mumps, when it is more serious, it may spread to the reproductive system, leading to inflammation of the testicles, which may result in enlarged testicles. 3. Inguinal hernia: It is usually formed when the inner ring of the groin is not closed, and a lump may be felt in the scrotum of the toddler, which may increase in size when he cries. Therefore, large testicles in toddlers may also be caused by inguinal hernia. In addition to the above factors, this symptom does not exclude that there are other possibilities, and patients are advised to go to the regular hospital in time for consultation and treatment.