To evaluate the effect of the tapered round pipe geometry,volumetric flow rate and gellant type or content on the pressure drop,the velocity and viscosity fields,the governing equations of the steady,incompressible,isothermal,laminar flow of a Power-Law,shear-thinning gel propellants in pipe were formulated,discretized and solved. A SIMPLEC numerical algorithm was applied for the solution of the flow field. Results show that the mean apparent viscosity decreases with increasing of the volumetric flow rate and increasing of the gellant content results in an increase in the viscosity. The results also show that the cone semi-angle can produce additional decrease in the mean apparent viscosity of the fluid. The mean apparent viscosity decreases significantly with increasing of the convergence angle of the pipe,and its value is limited by the Newtonian viscosity η_∞. The effect of the cone semi-angle on the mean apparent viscosity is more significant than that of the volumetric flow rate and the gellant type or content on the mean apparent viscosity. Additional decreasing of the viscosity results in an increase in the pressure drop with the increasing of cone semi-angle. It is important to pipe design that the viscosity decreasing and the pressure drop increasing are taken into account together.