The rheological behavior, apparent density and pore structure of low foaming PS were studied in this paper. The results show that the low foaming PS melt is pseudoplastic fluid. At lower temperature, the apparent viscosity of low foaming PS melt is lower than that of PS melt, higher at higher temperature. The activation energy of low foaming PS melt is lower than that of PS melt, which indicates that the processing temperature for low foaming PS may be lower than that of normal PS. At the same time, the non Newtonian index of low foaming PS melt is bigger than that of PS melt. Lower processing temperature leads to low foaming PS products with lower apparent density and good performance.