On the basis of the logarithm method, an operational effectiveness evaluation method is put forward. Through calculating the radar detection range to know whether there is an earlywarning aircraft in cooperation with or not, a specific expression of the change of the target ability parameters is given. Based on the Lanchester equation, an air combat model is established under the condition of the cooperation of the earlywarning aircraft. And the air combat process is simulated under five given conditions, the air combat process is simulated, and the simulation data and loss charts are given. The results show that after the installation of the data chain under condition of the earlywarning aircraft cooperative combat, so long as the military strength of our side exceeds a foe by 77.3％, our side will surely win victory.