Abstract: In this paper we reported the dynamic mechanical properties of series of SIS Star-shaped block copolymer measured by Rheovibron Viscoelastometer, which have the same composition, the same molecular weight of branch chain, but different degree of branching as well as the same degree of branching but different molecular weight of branch chain. We observed that the molecular weight of branch chain has serious influence on glass transition temperature for each phase and dynamic Young's moduli E', but the degree of branching has minor influence on glass temperature and evident influence on E'.