Rheologic behavior of the common Ryton-type poly(phenylene sulfide) (PPS) and Fortron PPS has been studied using a capillary rheometer. The effects of shearing rate, shearing stress, and temperature on the apparent viscosities of PPS are discussed. The non-Newtonian index and the activation energy of the viscous flow were obtained. The results show that the apparent viscosity of the Ryton PPS decreased obviously with increase of shearing rate or shearing stress, and with increase of the temperature, the apparent viscosity is not considerably decreased. On the contrary, the apparent viscosity of the Fortron PPS is more sensitive to temperature than to shearing rate and shearing stress.