A new topping cycle coal power generation process has been developed as a Japanese national project for a high efficiency power generation process. This process consists of a pressurized bubbling fluidized-bed coal gasifier and a pressurized bubbling fluidized-bed combustor which combined in series. To evaluate the performance and to determine specification and operation parameters of this process, it is extremely important to analyze the behavior and the performance of the system by a reasonable simulation model. A simulation model of this new process is developed in this paper. It is demonstrated by calculating results from this model that the carbon conversion in the gasifier, the composition and the heating value of the produced gas are strongly dependent on operating conditions. Heat recovery by steam in the combustor is controlled by the coal feed rate.