There is considerable interest in the effect of high energy radiation on triblock copolymer, SBS. Basheer and Dole have done some works about that(Basheer and Dole, 1982). In this paper, we study the effects of radiation crosslinking on the structure and mechanical properties of SBS, about which there have been no reports up to now. The following scientific problems are discussed: (1) The variation of glass transition temperatures with dose; (2) The effects of the ratio of B/S on the gel content; (3) Mechanical properties of the irradiated samples.