Abstract: In order to explore the damage threshold of the fast electromagnetic pulse (FRTEMP) to the transceiver of UAV, a UAV transceiver is taken as the equipment under test(EUT), and a type of pulse source along the GTEM chamber is used to generate the fast electromagnetic pulse to irradiate the transceiver. The transceiver's failure to work is taken as the criteria of electromagnetic pulse damage, and after then, the inner circuit of the transceiver is detected to determine the damaged device. The experimental results show that the electromagnetic pulse can cause damage to the transceiver of UAV, and the electromagnetic field threshold of the electromagnetic pulse is obtained. The damaged UAV transceiver mechanism analysis and testing results show that the local oscillator circuit damage makes the transceiver unable to output signals, and phase-locked loop (PLL) damage is the key reason why the oscillator is unable to work. Determination of the specific damaged device can provide a basis for the protection of vulnerable devices.