Abstract: The closed Brayton cycle system which uses the helium-xenon mixture as the working fluid is the most feasible technical solution to high-power thermoelectric conversion for space explorations. The high temperature helium-xenon gas regenerator is a key component of the closed Brayton cycle system, as its performance would significantly affect the power generation efficiency, the launching mass and the layout compactness of the system. Methods of computational fluid dynamics and traditional theoretical analysis were used to study the structure and molding process of high temperature helium-xenon gas microchannels, the relation between working temperature and regenerator effectiveness and the dependence of flow rate and performance parameters. The results show that using the engraving process as the microchannel molding process can lower the pressure drop by 40% and the mass by 17% without reducing the heat transfer performance of the regenerator. Under the condition of design parameters, setting up connection channels between the microchannels would not increase the heat exchange capacity. The regenerator effectiveness decreases as the flow rate increases, where an inflection point exists. With regard to design parameters of the regenerator which is going to be developed, the design flow rate should not exceed 0.24 g/s. The rationality of the regenerator structure could be determined by the ratio of heat exchange area to power with unit pressure drop and temperature drop. The rationality of the regenerator structure can be effectively improved by reducing the Raynolds number.