Abstract: The design of a low detectable supersonic inlet (DSI) involves the influence of multiple geometric parameters, making it challenging to fully reflect their impact on the inlet performance through a single parameter analysis alone. To address this issue, a non-intrusive polynomial chaos method was employed to study the low detectable supersonic inlet, by performing a sensitivity analysis of the inlet performance to various geometric parameters such as throat area, throat location, bump Mach number, bump forward amount, lip length, lip leading-edge radius, and inlet contraction amount under conditions of subsonic flow with high attacking angles as well as flow at the highest flight speed. Based on these findings, a selection design of inlets was conducted. The results reveal that the lip length is the most sensitive parameter, while both the bump Mach number and the bump contraction amount also contribute to the inlet performance improvement at low-speed flow with high attacking angles. After the selection design process, the total pressure recovery coefficient and the steady-state distortion index are increased and decreased by 3.1% and 35.5%, respectively, under the condition of the highest flight speed; the corresponding two values are 4.6% and 10.9% under the condition of low-speed flight with high attacking angles. These outcomes highlight the overall inlet performance can be effectively enhanced by appropriate selection of geometric parameters as well as attenuation or elimination of flow separation around the inlet lip or after the shock waves.