Using the finite element method (FEM), we analyze the characteristics of the surface plasmon polaritons of an elliptic cylinder metal wire at 0.5 THz. The field has properties of low absorption and low dispersion, which is similar to that of a cylindrical metal wire. The results show that, as the major-to-minor semi-axis ratio of the elliptic cylinder metal wire increases, the fields are gradually separated and concentrated to its tip regions, while the absorption keeps notably reducing, so the propagation length continually increases. Because of these properties, elliptic cylinder metal wire is appropriate for applications such as terahertz waveguide, focusing, and imaging, etc.