The scattering of actual radar targets is complex. Irregular shape and shielded structure increase the difficulty of scattering center modeling. The existing scattering center models do not consider these practical problems. In order to achieve higher modeling accuracy, the scattering center model needs to be modified. This paper gives specific modification methods for influence of the frequency dependence term of the scattering center model and the scattering intensity variation caused by irregular plane and shielded structure. Through numerical verification, the accuracy of the modified model in simulating the fluctuation characteristic of radar cross section of the complex target, two dimensional radar image and timefrequency representation characteristics is confirmed.