Testicular torsion is an urological emergency. It is a painful condition that requires prompt treatment once it is identified in order to protect the function of the testicle as much as possible. Testicular torsion is divided into intrasphincter torsion and extrasphincter torsion, and the causes are not the same. Extrasphincteric testicular torsion is most commonly seen in newborns and fetuses. In the late fetal and neonatal periods, the testicle has just descended into the scrotum and the introitus is not completely fused to the scrotal wall, therefore, the testicle, epididymis and sheath as a whole are more free and prone to torsion. In contrast, intrasphincteric testicular torsion is most often seen in adolescents, and the causes are closely related to anatomical abnormalities: the testicular tether, the lead band is too long or missing, increasing the mobility of the testis; the sheath wall layer is too high at the stopping point on the spermatic cord; the testicular spermatic cord is completely encircled by the sheath, with no attachment point to the scrotum at the posterior and lateral side lacking fixation; and the testis is incompletely descended or ectopic. In addition, the more active reflex of the levator muscle during puberty is also a cause of testicular torsion. In summary, both intrasphincteric testicular torsion and extrasphincteric testicular torsion are directly related to the development of the testis, and incomplete testicular descent and the absence of certain tissues that hold the testis in place are the main causes of testicular torsion.