A TM-mode dielectric resonator comprises a top-end hollow cylindrical part, a bottom-end hollow cylindrical part and a hollow transition part, wherein the external diameter of the top-end hollow cylindrical part is D, the external diameter of the bottom-end hollow cylindrical part is d, the external diameter D of the top-end hollow cylindrical part is larger than the external diameter d of the bottom-end hollow cylindrical part, an upper end of the hollow transition part is connected with the top-end hollow cylindrical part, a lower end of the hollow transition part is connected with the bottom-end hollow cylindrical part, the external diameter of the hollow transition part is uniformly reduced from D to d at a fixed taper angle Theta, the inner diameters of the top-end hollow cylindricalpart, the bottom-end hollow cylindrical part and the hollow transition part are maintained unchanged, and a resonant frequency of the TM-mode dielectric resonator is adjusted by polishing at least oneof a length L1 of the top-end hollow cylindrical part and a length L2 of the bottom-end hollow cylindrical part.