The invention discloses a flight path design method facing optimal reconnaissance. The method is characterized by comprising the following steps: in an initial segment, an aircraft using an interstage sliding method to increase flight path time; in a middle segment, according to flight path points and target information obtained by reconnaissance loads, performing iterated revision on location deflection angles, to increase target accumulated reconnaissance time; in a last segment, satisfying stagnation heat flux constraint, flight attack angle constraint, and flight speed constraint, if the aircraft is pushed down, taking an attack angle and the state variable corresponding to a push-down point into a motion differential equation for integration; establishing a flight whole time optimization function, segmenting the flight path according to the initial stage, the middle segment, and the last segment, using a flight path planning search algorithm to perform iterative solution on the whole time optimization function, to determine optimal controlled variable of each segment. The method can rapidly design flight paths which satisfy various reconnaissance constraints, and the whole reconnaissance time is optimal.