The invention relates to the technical field of aviation air inlet channels, in particular to a boundary-layer-free separation channel air inlet channel which is used for solving the problems that inthe prior art, a boundary layer separation channel of an air inlet channel increases the windward area of an airplane, so that the aerodynamic resistance of the airplane is increased, the radar stealth performance is reduced, and the air inlet channel is difficult to manufacture. The boundary-layer-free separation channel air inlet channel comprises an air inlet pipeline, a lip and a bulge which are sequentially formed into a whole, the bulge comprises a step face and a bulge main face which are mutually formed into a whole, the step face comprises an upper step face body and a lower step facebody, and a sweepback angle is arranged on the edge of the lip. A boundary layer separation channel is omitted, the angle emitter effect of boundary layer separation channel electromagnetic waves iseliminated, the windward area and resistance of an airplane are reduced, and manufacturing is easier; the sweepback angle design is adopted for the lip and the bulge, the electromagnetic wave mirror surface effect under the main use posture of an airplane is reduced, and therefore the stealth effect of the lip is improved.