The invention discloses a low-profile directional diagram reconfigurable substrate integrated waveguide H-shaped horn antenna. The horn antenna mainly comprises three parts such as an electricity adjustable feed network, a radiating element and a direct-current biasing circuit. According to the directional diagram reconfigurable substrate integrated waveguide horn antenna disclosed by the invention, 0-degree, 90-degree, 180-degree and 270-degree scanning in a main wave beam direction on the horizontal plane can be realized, and the horn antenna has the characteristics of low profile, broad band, simple structure, convenient operation and the like.