Abstract: Combining the constitutive equation of Casson fluid with the force-balance relation and the energy equations of non-Newtonian fluid, the velocity and temperature profiles for pipe flow of Casson fluid are obtained. The study results show that there is plunger-cylinder flow in the center of the pipe for the action of Casson yield stress τ_c. The radius r₀ of the plunger-cylinder is in direct proportion to τc and inverse proportion to △p/L. The velocity μ₀ of the plunger-cylinder decreases with τ_c increases. The temperature in the plunger-cylinder is identical and from the boundary of the plunger-cylinder to the pipe wall the temperature gradually decreases. Furthermore, the nearer to the pipe wall, the faster the temperature decreases.