Abstract: In order to study the security effect on a certain radio fuze of lightning electromagnetic pulse (LEMP), and confirm the energy coupling channel and the effect rules, an experiment system is constructed and LEMP irradiation experiments are done. Experiment results show that the best coupling pose is that the fuze is vertically upward, and the bomb body axis and the antenna plane are perpendicular to the radiation field propagation direction. The bomb body is the main energy coupling channel. Different irradiation wave has different threshold interference field. Under the 152 mm bomb body, the threshold interference fields of the irradiation waves of 1.2/50, 5.4/70, 0.25/100 and 10/350 s, are about 74, 60, 65 and 75 kV/m. The effect mechanism of LEMP is that the irradiation energy couples to the input of the executive circuit. The pulse width of the coupling signal satisfies the requirement of the startup pulse width, leading to the miss-action of the executive circuit.