Abstract: The scattering characteristics in terahertz band of uniform partition and non-uniform unstable conducting target with different roughness surface is studied. This paper proposes to apply the modeling concept of randomly rough surface to the modeling of uniform partition and non-uniform unstable rough surface target in terahertz band, which is different from the modeling method of using formulae. Two physical quantities which are used to describe the RMS height and correlation length of rough surface are applied to adjust the roughness of target surface. Firstly, the rough surfaces of uniform partition and non-uniform unstable target are modeled by Gaussian random surface, then a combined method of physic optics and equivalent current is employed for simulation. The THz wave scattering characteristics of different rough surface target with different incident angles, different frequencies and different roughness are analyzed and discussed. Finally, the relevant conclusions are drawn.