A novel tailoring method for conducting Electromagnetic Compatibility(EMC) testing on applicable test range,frequency band and limit size is presented for better use of national military standards GJB151A and GJB152A-97. After calculations of common-mode and differential-mode on rectifier and brute force filter,the limits of CE101 testing can be broadened up to 5 dB at 400 Hz in the conditions of the power of Equipment Under Test(EUT) below 0.2 kVA and load circuit above 1 A. Based on the topology structure of switch power source and typical switch current wave, the limits in CE012 test can increase by 10 dBμV when the testing frequency band width is below 2 MHz. According to the scheme of RE101 testing, the limits of magnetic emission measured from 7 cm away emission source are 100 mG at 30 Hz, 25 mG at 60 Hz and 6.6 mG at 120 Hz. Based on the coupling mode of emission source and receive antenna, it is confirmed that the limits of RE102 should be strictly controlled in 2~30 MHz bandwidth. The UAV is tested in real flying ground by 410A susceptivity testing system and by simulated Electromagnetic Pulse(EMP) test according to military testing method GJB3567-99, the results reveal that the air-borne equipment based on this tailored testing method can work normally and do not be degraded, which shows that this tailoring method can satisfy the requirement of EMC of UAV.