The Inverse Synthetic Aperture Radar(ISAR) technology is applied to terahertz frequency band, and the original data are obtained by scanning smooth surface objects and complex surface objects. The obtained 3D data are processed based on fast Fourier transform, and the transverse and radial high resolution terahertz 3D target reconstruction is realized. After the spherical wavefront correction of the wavenumber domain echo complex signal to the plane wavefront phase compensation, interpolation processing and spatial image threshold denoising processing, the reflection coefficient of the target is extracted from the three-dimensional space and its spatial position information is retained, so as to complete the reconstruction of the three-dimensional target.