The electromagnetic security of datalink becomes an outstanding issue for restricting the development of an Unmanned Aerial Vehicle(UAV). To improve the adaptability of the UAV’s datalink in the electromagnetic environment, a test method of electromagnetic radiation effects on the dynamic datalink is designed due to variable electromagnetic susceptibility depending on the flight state. Then the test of continuous wave radiation effects on the datalink is conducted. The results show that the electromagnetic susceptibility depends on the operation signal power. The electric field thresholds of the in-band interference is lower than 1 V/m under normal operations for UAV, but the corresponding Automatic Gain Control(AGC) voltage is the largest, reaching 190 V. Although the anti-interference capability of the datalink is weak, but its error tolerance performance is good. The increasing trend of the number of bit errors with the increase of Electromagnetic Interference(EMI) signal power is obvious. When the amount of bit errors approaches the limited maximum, the uplink can still work properly. Besides, the frequency offset EMI may suppress the BER increasing process at the critical lost-link state resulting in the disruption of the datalink. The corresponding susceptibility threshold becomes larger as the frequency offset increases, but the corresponding AGC voltage is relatively reduced.