This paper presents a fiber beam-column model for seismic response analysis of steel-concrete composite structures through the customization of the large generic FE package MSC.Marc (2005r2). The model combines the fiber section model and the displacement-based perfectly-bonded beam element. Based on the characteristics of composite sections usually used in practice, the definition approach of composite sections and the discrete process of section fibers have been proposed. The uniaxial constitutive laws of the concrete, steel and reinforcement materials have been focused on. The proposed concrete constitutive model covers the ordinary, high-strength and confined concrete material and the hysteretic law has been improved to consider the strength degradation phenomenon due to repeated unloading and reloading so that the model can more reasonably and accurately trace the actual complex nonlinear behavior. The fiber beam-column model has been applied to the nonlinear analysis of variable types of members, including ordinary reinforced concrete members, steel-concrete composite beam members, and concrete filled steel tubular members, under variable load cases. Good correlations between numerical and experimental results demonstrate that the proposed model provides a reliable and powerful tool for seismic response analysis of steel-concrete composite structures due to its accuracy, broad applicability, efficiency, rapid and stable numerical solution, as well as powerful and convenient pre-processing and post-processing.