The fine structure of conductor surface can cause impact on the amplitude, phase of the scattered fields at THz frequencies. For analyzing these effects, periodic and reticulate structure whose dimension assimilates to wavelength, and rivets array structure with Perfect Electric Conductor(PEC) are taken as examples to illustrate the characteristics of the scattered fields of different elevation angles in radar imaging. The convolution back projection algorithm is utilized to image the multi-angles, multi-frequency monostatic scattered fields echo data generated by the commercial software platform. The simulation results show that the scattering characteristics of different fine structures differ greatly. By employing the range profile analysis method, the reasons that form different features in the image domain are obtained. It is found that the mechanism of different image features can be resorted to the effects of coherent cancellation, coherent enhancement and the virtual ghosts. These results show that the THz wave owns an unique depictive ability for the fine structure.