Quasi-one-dimensional model is the most effective way to realize the rapid iterative design of the overall scheme and control system of RBCC aircraft and has become a research hotspot. In the current research, the quasi-one-dimensional model of RBCC propulsion system is simplified. The model does not include physical characteristics such as wall heat transfer, boundary layer change, specific heat ratio change and transonic flow singularity, which makes the accuracy of the model low and cannot adapt to flight control in large airspace. A RBCC model with high accuracy and adaptability to wide-speed fly is established in this paper. Firstly, based on the laws of kinetic energy conservation and energy conservation, the thrust model of ejection mode is established. Secondly, the quasi-one-dimensional flow control equation is deduced, and the physical mechanism models of core flow area, transonic flow, pre-combustion shock train, heat release law and mixing efficiency are established. On this basis, the quasi-one-dimensional flow model of RBCC dual-mode ramjet is established. Thirdly, based on the law of momentum conservation, the mathematical model of rocket mode is deduced, and the thrust model of rocket mode is established. Finally, the accuracy of the quasi-one-dimensional model is verified by CFD numerical simulation and direct-connect experiment. Taking a typical RBCC launch vehicle as an example, the wide-speed performance of the RBCC propulsion system is calculated and analyzed.