A multi-band antenna, wherein the multi-band antenna comprises a reflection panel, at least one high-frequency unit, and at least one low-frequency unit, each high-frequency unit comprises a balun structure, a coupling structure, and a radiation arm structure, the balun structure comprises two balun sub-structures, the coupling structure comprises two coupling sub-structures, and the radiation arm structure comprises two radiation arms, wherein the at least one high-frequency unit and the at least one low-frequency unit are disposed on the reflection panel; in each high-frequency unit, each coupling sub-structure is separately electrically connected to one balun sub-structure and one radiation arm; and the coupling sub-structure is configured to: transmit a signal whose frequency is higher than a preset threshold, and block a signal whose frequency is lower than the preset threshold, and wherein the high-frequency unit further comprises a substrate, and the substrate is vertically disposed on the reflection panel; and the two radiation arms are symmetrically disposed on one end that is of the substrate and that is away from the reflection panel, the two coupling sub-structures of the coupling structure are symmetrically disposed on a surface of the substrate, and the two balun sub-structures of the balun structure are symmetrically disposed on the surface of the substrate, wherein the coupling sub-structure comprises a first coupling stub, a second coupling stub, and a third coupling stub, wherein the third coupling stub is separately coupled to the first coupling stub and the second coupling stub; the first coupling stub, the second coupling stub, and the corresponding balun sub-structure are disposed on a first surface of the substrate, and the third coupling stub is disposed on a second surface of the substrate; and the first coupling stub is electrically connected to the corresponding balun sub-structure, and the second coupling stub is electrically connected to the corresponding radiation arm. the at least one high-frequency unit and the at least one low-frequency unit are disposed on the reflection panel; in each high-frequency unit, each coupling sub-structure is separately electrically connected to one balun sub-structure and one radiation arm; and the coupling sub-structure is configured to: transmit a signal whose frequency is higher than a preset threshold, and block a signal whose frequency is lower than the preset threshold, and wherein the high-frequency unit further comprises a substrate, and the substrate is vertically disposed on the reflection panel; and the two radiation arms are symmetrically disposed on one end that is of the substrate and that is away from the reflection panel, the two coupling sub-structures of the coupling structure are symmetrically disposed on a surface of the substrate, and the two balun sub-structures of the balun structure are symmetrically disposed on the surface of the substrate, wherein the coupling sub-structure comprises a first coupling stub, a second coupling stub, and a third coupling stub, wherein the third coupling stub is separately coupled to the first coupling stub and the second coupling stub; the first coupling stub, the second coupling stub, and the corresponding balun sub-structure are disposed on a first surface of the substrate, and the third coupling stub is disposed on a second surface of the substrate; and the first coupling stub is electrically connected to the corresponding balun sub-structure, and the second coupling stub is electrically connected to the corresponding radiation arm.