An empirical formula of collision frequency has been used for years to calculate the collision frequency of aircraft plasma sheath. But the formula ignores the influences of electron-electron impact, electron-ion impact, and electro-magnetic (EM) wave driving effect on the collision frequency. To remedy these deficiencies, this paper proposes a segmentation calculation method. Based on the plasma kinetic theory, combined with real flow conditions and synthesizing the influences of electron-electron impact, electron-ion impact and EM wave driving effect together, this method defines a new parameter, ionization-to-thermal motion ratio, to calculate the collision frequency segmentally. Theoretical analysis and simulation results demonstrate that this method is closer to the truth than the empirical formula when ITR is greater than 5.