Abstract: The glass transition temperature of regular star-shaped block copolymers of polystyrene and polyisoprene with different arm length and branch degree are measured by linear dilatometer and dynamic Rheovibron Viscoelastometer. The values of T_gI and T_g(S) depend on the morphology, branch degree and the arm length of these polymers. The effect of these factors on the glass transition temperature of dispersed phase, T_g(S), is found to be more noteworthy. The intermediate phase relaxation is suggested.