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 . <EOS>