A scheme of employing high-temperature gas source instead of normal-temperature air as the ejection gas source is proposed， and an air/alcohol gas generator based on aeroengine annular combustor structure is designed to meet the miniaturization and maneuverability of a high-energy chemical laser pressure recovery system. Meanwhile， CFD software is adopted to simulate the flow field of gas generator， and obtain the velocity， pressure， and temperature fields of gas generator in cold and combustion conditions. Some simulation results are compared with theoretical calculation and experimental values. The research shows that the design of the gas generator is reasonable， and there is no air flow separation at the diffuser and the junction of the two-channel cavity， without overflow at the cap. The recirculating zone of the main combustion zone is obvious with moderate scale， which is conducive to combustion organization and guides the location layout of high-energy electric fire devices. The air flow ratio is reasonable， and the jet depth of the main combustion hole and mixing hole meets the combustion and mixing requirements. The total pressure recovery coefficient of the combustion combustor reaches 96.7% with the combustion efficiency of 98.4%， which realizes efficient combustion. Additionally， the theoretical calculated values and experimental results in the same working conditions verify the rationality and feasibility of the numerical simulation method.