This paper investigated the microscopic imaging and detection of subsurface metal micro/nano structures using Terahertz scattering-type near-field optical microscopy (THz s-SNOM). For the first time, a self-built THz s-SNOM system was employed to measure the Terahertz near-field of gold micro wires covered with hexagonal boron nitride (h-BN) film on the surface, resulting in near-field microscopy images with nanometer-level spatial resolution and high contrast. Combined with full-wave numerical simulation, the spatial resolution, near-field scattering signal intensity, and imaging contrast of THz s-SNOM for detecting subsurface metal micro/nano structures were analyzed. The study shows that THz s-SNOM has excellent subsurface microscopic imaging and detection capabilities and can be applied to the subsurface structure characterization and defect detection of micro/nano electronic devices.