The application provides a dielectric resonator, including a main body and a surrounding wall, the surrounding wall protrudes from one surface of the main body, and the surrounding wall surrounds and forms a cavity area on the surface of the main body, and the surrounding wall makes the cavity area Separated from the outer space of the surrounding wall, the surrounding wall includes a top surface, an inner surface and an outer surface, the inner surface and the outer surface are oppositely arranged and connected between the top surface and the main body , the top surface is located on the surface of the surrounding wall away from the main body, the inner side is the surface of the surrounding wall facing the cavity area, and the outer side faces the outside of the surrounding wall space, the top surface is covered with a metal layer, and the inner and / or outer surfaces are also covered with a metal layer. The application also provides a filter. The dielectric resonator improves the leakage between the open surfaces of the filter, facilitates pushing away the harmonics, and improves the high-frequency suppression performance.