In signal detection of Airborne Early Warning (AEW) radar under actual combat environment, the object signal must contend against sidelobe clutter, noise and jamming.The ratio of signal to the sum of sidelobe clutter, noise and jamming determines the operating range of the AEW radar, in which the sidelobe clutter power calculation is most difficult under different terrain and different PRF working model.Considering the benefit of the radar signal processing, we derived the universal formula of sidelobe clutter power calculation based on the analysis of ground and sea clutter characteristics.The operating range equation of AEW radar under the clutter and jamming environment was also given.The simulation results demonstrate the correctness of the sidelobe clutter power calculation formula and the operating range equation.