The effects of fiber concentration, shear rate and temperature on shear viscosity and die swell have been investigated for carbon fiber-filled polyvinylidene fluoride melt. The rheological properties were measured by using Instron capillary rheometer Flow curves were obtained from 210℃ to 290℃ over the cross head speed 0.2 to 20cm/min. The apparent viscosities of PVDF/carbon fiber melts decreased with an increase in temperature and increased with increasing the amount of carbon fiber. The relative viscosities at constant shear rate was increased with increasing carbon fiber content of composites and increasing temperature, and decreased with an increase in shear rate. It can be, therefore, concluded that relative viscosity was a function of temperature and shear rate as well as fiber volume fraction, as one might expect. The activation energy was found to decrease with increasing shear rate and increasing carbon fiber content of the composites. However the die swell ratio was not affected by the various medium. and the die swell ratio was decreased with increasing the amount of carbon fiber, temperature. and sheat rate.