A dielectric filter, comprising: a dielectric body, wherein a surface of the dielectric body is covered with a conductive layer; and a wideband filtering structure and a narrowband filtering structure, wherein: both are disposed in the dielectric body; a passband of the narrowband filtering structure is located within a passband of the wideband filter structure; the wideband filtering structure comprises a groove and at least one first resonator, wherein: the groove is disposed on a first surface of the dielectric body and is configured to adjust a frequency position of the passband of the wideband filtering structure; the first resonator comprises a through hole and a loop, the through hole penetrates the bottom of the groove and a second surface of the dielectric body, and a hole wall of the through hole is covered with the conductive layer; the loop is located on a bottom surface of the groove, disposed around an opening of the through hole and not covered with the conductive layer; and a side surface of the groove and a part, other than the loop, of the bottom surface of the groove are covered with the conductive layer; and the narrowband filtering structure comprises at least one second resonator, wherein: the second resonator comprises a blind hole disposed on the first surface or the second surface of the dielectric body, and a hole wall and a bottom surface of the blind hole are covered with the conductive layer; and the first surface and the second surface of the dielectric body are disposed oppositely; wherein the wideband filtering structure further comprises at least one adjustment through hole, wherein: a hole wall of the adjustment through hole is covered with the conductive layer; and the adjustment through hole penetrates the bottom of the groove and the second surface of the dielectric body, and the adjustment through hole is configured to adjust a harmonic suppression capability of the dielectric filter. a dielectric body, wherein a surface of the dielectric body is covered with a conductive layer; and a wideband filtering structure and a narrowband filtering structure, wherein: both are disposed in the dielectric body; a passband of the narrowband filtering structure is located within a passband of the wideband filter structure; the wideband filtering structure comprises a groove and at least one first resonator, wherein: the groove is disposed on a first surface of the dielectric body and is configured to adjust a frequency position of the passband of the wideband filtering structure; the first resonator comprises a through hole and a loop, the through hole penetrates the bottom of the groove and a second surface of the dielectric body, and a hole wall of the through hole is covered with the conductive layer; the loop is located on a bottom surface of the groove, disposed around an opening of the through hole and not covered with the conductive layer; and a side surface of the groove and a part, other than the loop, of the bottom surface of the groove are covered with the conductive layer; and the narrowband filtering structure comprises at least one second resonator, wherein: the second resonator comprises a blind hole disposed on the first surface or the second surface of the dielectric body, and a hole wall and a bottom surface of the blind hole are covered with the conductive layer; and the first surface and the second surface of the dielectric body are disposed oppositely; wherein the wideband filtering structure further comprises at least one adjustment through hole, wherein: a hole wall of the adjustment through hole is covered with the conductive layer; and the adjustment through hole penetrates the bottom of the groove and the second surface of the dielectric body, and the adjustment through hole is configured to adjust a harmonic suppression capability of the dielectric filter. the groove is disposed on a first surface of the dielectric body and is configured to adjust a frequency position of the passband of the wideband filtering structure; the first resonator comprises a through hole and a loop, the through hole penetrates the bottom of the groove and a second surface of the dielectric body, and a hole wall of the through hole is covered with the conductive layer; the loop is located on a bottom surface of the groove, disposed around an opening of the through hole and not covered with the conductive layer; and a side surface of the groove and a part, other than the loop, of the bottom surface of the groove are covered with the conductive layer; and the narrowband filtering structure comprises at least one second resonator, wherein: the second resonator comprises a blind hole disposed on the first surface or the second surface of the dielectric body, and a hole wall and a bottom surface of the blind hole are covered with the conductive layer; and the first surface and the second surface of the dielectric body are disposed oppositely; wherein the wideband filtering structure further comprises at least one adjustment through hole, wherein: a hole wall of the adjustment through hole is covered with the conductive layer; and the adjustment through hole penetrates the bottom of the groove and the second surface of the dielectric body, and the adjustment through hole is configured to adjust a harmonic suppression capability of the dielectric filter.