Abstract: There are some especial cascades which can be used to do some especial study, including ladder cascade, square cascade and other cascades. This paper put forward a sort of cascade model that is “T” cascade is used to enrich the constituent of middle isotope. The cascade is in the same shape with letter of “T”, and it can use one feed and three produces to enrich the constituent of middle isotope to the needful abundance by one time. The cascade used to enrich the isotope of ¹³¹Xe that can make the abundance of ¹³¹Xe isotope to 90% or more for target by one time, and separating power of two cascades is slightly less than separating power of “T” cascade. The result can show that “T” cascade can enrich the constituent of middle isotope to the needful abundance by one time.