A self-developed simulation platform of natural gas internal reforming solid oxide fuel cell (IRSOFC)-gas turbine (GT) hybrid generation system was described in this paper. It fully reflected the concept of multi-level and hierarchical modeling. For SOFC, there are the general electrochemical model including both H(2) and CO oxidation, the advanced electrochemical model considering surface diffusion and competition absorption, the mechanistic transport model and its approximate analytical solution. With a set of uniform governing equations for both planar and tubular SOFCs, description of flow and heat transfer in cell-level models provides the boundary conditions for the different types of electrode-level models. And the models with different complexity of other balancing components were also developed for different system requirements. Via the interface configuration and graphic specification in the commercial environment of gPROMS, it fully realized the flexible configuration and modular design for the different cases. By comparison with the experimental data of the Siemens-Westinghouse 220 kW demonstration SOFC-GT hybrid generation system, our model library was validated with better performance than the advanced power system analysis tool (APSAT). And the simulation platform can be further used for the performance prediction, system optimization and controller design. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.