Abstract: The glass transition temperature T_gand T₁₁relaxation of a series of regular star-shaped polystyrenes were measured by tortional braid analyzer(TBA) and linear dilatometer. The results show that the T_gof star-shaped polymer increases with increasing branching degree when the molecular weights of branch chains are the same, but it is lower than that of linear polystyrene of the same molecular weight. The liquid₁-liquid₂relaxation temperatue T₁₁and the strength of loss peak of star polystyrene also depend on branching degree. Two-T_gtransitions in star polystyrenes with DVBmicrogel nodule were proved by comparing two type of star polystyrenes.