Non-metallic materials are being used increasingly as engineering materials in a Wide range of applications. This work introduces u numerical solution for pure torsion equation of a continuously homogeneous prismatic bar, which is cut longitudinally from a hollow cylinder. having a material with rectilinear anisotropy and n circular sector cross section. The lateral surface of the prism is free from external forces, and from all restraints. Body forces are absent, and the ends are subjected to distributed forces, which are leading to twisting moments of opposite directions. Only two stress components are different from zero, and the remaining four vanish. The problem is constructed using a small physical parameter, which characterizes the material anisotropy. A mathematical model is derived using Fourier series analysis. and the stress components are obtained as conversion expansions. Computer program is designed. and illustrative examples for orthotropic and non-orthotropic materials are introduced for showing the effectiveness of the suggested solution. Acceptable numerical results are obtained, and convergence is discussed.