Abstract: With the continuous development of large reflector antenna technology, higher requirements are put forward for the diversification and integration of equipment functions. Feed as the core of large reflector antenna, its performance determines the overall characteristics of reflector antenna. In this paper, a dielectric loaded dual band horn antenna is proposed based on the hybrid mode of dielectric waveguide. The antenna works in X (7.25-7.75 GHz) and Ka (21-22 GHz) band. The eigenvalue theory is used to solve the expression of electromagnetic field in double-layer dielectric waveguide. By changing the topology of double-layer dielectric waveguide, the mixed mode HE₁₁ of surface wave state is formed. In X-band, due to the small aperture of the horn, the E-plane and H-plane equivalent pattern is formed. In Ka band, by changing the shape of dielectric cone, the similar point source radiation is formed, and the E-plane H-plane equivalent pattern with low cross polarization is also formed. The feed is processed and tested, and the test pattern is in good agreement with the simulation results. The feed is applied to the 13 m ring focal reflector antenna of the satellite ground receiving system, and is verified that the aperture efficiency of the antenna in the working frequency band is more than 60%.