Abstract: The composite electromagnetic scattering characteristics of tank target above complicated ground rough surface are studied. Based on the Monte Carlo method, the Gauss spectral function is used to simulate different ground surfaces with different statistic properties. Weighted inverse tangent function is presented to filter in order to structure the boundary and connect adjacent regions. The geometrical model of composite rough surface of complicated ground environment is established. Aiming at fast and accurately computing composite scattering from tank target above complicated ground rough surface, a kind of new hybrid method is proposed, in which iterative physical optics (IPO) is used to calculate the multiple coupling of facets between target and environment and method of equivalent currents (MEC) is applied to meliorate edge diffraction. The curve of bi-static scattering coefficient (BSC) of complicated ground rough surface is analyzed. The influences of incident angle, root mean square (RMS), correlation length and construction on composite electromagnetic scattering characteristics are discussed. This research provides theoretical basis for detection of tank target above complicated ground rough surface. Numerical results can be used for reference in the filed of radar object detection and identification.