Abstract: Electromagnetic metamaterials have excellent electromagnetic properties, which meet the needs of aircraft radome. This paper simulates the DC discharge along the surface and combined gap of the electromagnetic metamaterial radome under the background electrostatic field environment of the aircraft in thunder cloud. The experimental results show that the surface discharge morphology of the resonant ring electromagnetic metamaterial is a linear discharge along the periodic direction or 45° with the periodic direction of the metamaterial; when the deviation degrees φ is 0°, 15°, 30° and 45°, respectively, the flashover field strength per unit distance along the surface of the resonant ring electromagnetic metamaterial is 1.46 kV/cm, 1.57 kV/cm, 1.74 kV/cm and 1.76 kV/cm, respectively. When the deviation angles φ is 30° and 45°, the flashover field strength per unit distance along the surface is larger than that when the deviation angle φ=0° and 15°. Furthermore, the combined gap DC discharge of metamaterials is studied. It is found that when the needle plate gap is small (D=5 cm), the discharge attachment point falls in a large area below the needle electrode, and when the needle plate gap is large (D=15 cm), before reaching the breakdown voltage, the self discharge phenomenon will occur between the microstructure units, and the discharge attachment point will fall in a small area directly below the needle electrode. The breakdown voltage can be significantly increased by adding skin. The installation of shunt bars will cause the failure of lightning receiving. Shortening the distance of shunt bars is an effective means to improve the lightning protection effect of radome. This measure will reduce the breakdown voltage, and the corresponding lightning receiving rate is improved.