Abstract: The glass transition temperature T_g and relaxation temperature T₁₁ of a series of regular star-shaped polystyrenes were measured by using torsional braid analyzer(TEA) and linear dilatometer.The results showed that T_g for star-shaped polymer increases with increas-ing branching degree whan the molecular weights of branch chains arethe same,but it is lower than that of linear polystyrene with the same molecular weight.The liquid₁— 1iquid₂ relaxation temperature T₁₁ and the intensity of loss peak of star polystyrene also depend on branching degree.Two-T_g transitions in star polystyrenes with DVBmicrogel nodule were proved by comparing two types of star polystyrenes.