The different size of testicles may be a normal physiological difference, or it may be related to varicocele, syringomyelia and other diseases. 1. Physiological differences: under normal circumstances, if the male testicles are different in size or texture, it is generally a normal physiological difference, but if the difference in volume is large, we need to consider that it may be caused by diseases. 2. Varicocele: The cause of varicocele may be related to venous valve insufficiency, venous return obstacle and other factors. The patient mainly manifests the enlargement of the lateral scrotum, accompanied by pain, swelling and other phenomena. 3. Syringomyelia: the cause of syringomyelia may be related to chronic inflammation of the syringomyelia, scrotal surgery, developmental delay and other factors. If there is more fluid in the testicular syringomyelia cavity on one side, it may lead to enlargement of the scrotum, accompanied by tugging pain, falling sensation and so on. If the testicles are not the same size on both sides, after excluding physiological differences, it is recommended to visit regular hospitals for examination to clarify the cause.