Abstract: Aiming at the independently developed FADS system of the air-breathing air-to-air missile, the calibration is carried out by FD-12 wind tunnel. The technical characteristics of the wind tunnel calibration test are analyzed. The wind tunnel calibration scheme is proposed to avoid the step shock wave by using the variable length pole, mainly including the pole design, machining and installation of the model and the air tightness detection of the pressure pipe. The second calibration is done in FD-12 wind tunnel.The experimental results show that:in the range of Mach number from 2.0~3.5, the measurement error of FADS system achieves the design goal:the error of the static pressure is less than 490Pa (less than 3%), the error of Ma is less than 0.1, and both errors of the angle of attack and the angle of side slip are less than 0.5°. Compared with the calibration at first time, the errors of the flow parameter measurements are all reduced, especially for the Ma2 status where the maximum relative error of the static pressure decreases from 11.5% to 3.0%, the maximum error of Ma decreases from 0.15 to 0.10, the maximum error of angle of attack decreases from 2.5° to 0.5°, and the maximum error of angle of side slip decreases from 1.2° to 0.5°. The research results can provide technical reference for the design of FADS system.