Abstract: Geometric design method of mixed-compression fixed-geometry axisymmetric supersonic ramjet inlet was presented.Performance calculations of inlet under on-or off-design conditions were carried out with special attention to the detached bow shock calculation during subcritical operations.The influence of flight Mach number and altitude on inlet critical condition performance has been evaluated.The inlet-engine matching mechanism was investigated, and the fuel supply characteristics were obtained to maintain the optimum inlet performance.The successful study provides a good reference to the design of ramjet supersonic inlets.