Autonomous reconnaissance is an automatic and intelligent reconnaissance mode of UAV-borne photoelectric payload. Parameter calculation is the premise of autonomous reconnaissance application. The autonomous reconnaissance mode of UAV-borne photoelectric payload was first introduced, then the flight speed and altitude of autonomous UAV cruise, the sensor field angle of view, pitch angle, scan speed and scan angle of photoelectric payload were calculated, the physical meaning and relationship of each parameter were analyzed, and the influence of each parameter on target recognition rate and recon time was analyzed. Finally, simulation calculation and analysis were carried out with examples, and the existing problems in practical application were pointed out, which provided a theoretical basis for practical application of this mode.