A phased array antenna for high-power microwave applications is proposed. The horn antenna is used as the array element. The feed structure adopts a back-feed coaxial-waveguide converter and the end of the coaxial probe is thickened to better realize the mode conversion. The triangular grid array is selected to achieve a wide scanning angle by adjusting the pitch spacing of the element. In the 8-9GHz frequency band, VSWR is less than 2.2, the power capacity of the antenna element in the air is up to 11kW, and the array scanning angle is increased to $\pm \mathbf{30}^{\circ}$, so it has certain high-power microwave application value.