Abstract: In order to realize long-distance microwave wireless power transmission, the transmitting antenna should satisfy the needs of high power, high gain, low loss, and simple structure. To meet the above requirements, this paper designs an all metal Fabry-Perot cavity antenna. The whole antenna consists of a metal cavity, a waveguide feed port and a double-layer metal grid covering layer. The size of the covering layer is 3 λ0 × 3 λ0, λ0 is the corresponding working wavelength. Each layer of the metal grid contains 9×9 units. The designed double-layer covering layer can be regarded as an electromagnetic band gap structure Electromagnetic Band Gap. By optimizing the thickness and spacing of the double-layer metal grid cells, the simulations show that the double-layer covering layer achieves a broadband transmission characteristic of insert loss is less than 3dB from 9.72GHz to 10.3GHz. The gain of the antenna is improved because the amplitude and phase of the microwave radiated from the feed source is modified by the EBG structure. According to the simulationresults, the gain of the antenna is 97dBi when the double layer is not loaded, and the gain can be increased to 17.76dBi when the double layer is added. In order to verify the above design and simulation, a Fabry-Perot cavity antenna with all metal structure is fabricated. The measured results show that the antenna achieves a high gain of 1731dBi at 10GHz and an impedance bandwidth of echo loss is above 10dB from 9.51GHz to 11.42GHz.