Abstract: This paper focuses on multi-band fusion imaging. A method based on high-precision parameter estimation of Geometrical Theory of Diffraction (GTD) model is given. It makes use of the phase difference of pole and scattering coefficient between the all-pole model of each sub-band to estimate the incoherent components. The gapped-data amplitude and phase estimation algorithm is adopted to fill up the gapped band. Finally, fusion data is gained by high precision parameter estimation of geometrical theory of diffraction -all-pole model with full-band data. The simulation indicates that the resolution of 1D range profile and 2D ISAR image based on this method is better than that of sub-band. In this way, the effectiveness of the method is verified.