An ultra-wideband non-metal horn antenna (100, 301, 901, 1200), comprising: an impedance matching member comprising a first end and a second end opposite to each other, wherein the first end of the impedance matching member comprises a first tenon portion, and an end surface of the second end of the impedance matching member is provided with a first recessed structure, wherein the first recessed structure comprises a first protruding portion and a first groove structure surrounding the first protruding portion; a field adjustment member (130, 1230), which comprises a first end (131, 1231) and a second end (132, 1232) opposite to each other, wherein an end surface of the first end (131, 1231) of the field adjustment member (130, 1230) is provided with a first trench structure (131a, 1231a), and an end surface of the second end (132, 1232) of the field adjustment member (130, 1230) is provided with a second recessed structure (134, 1234), wherein the second recessed structure (134, 1234) comprises a second protruding portion (134a, 1234a) and a second groove structure (134b, 1234b) surrounding the second protruding portion (134a, 1234a), and a top surface (135, 1235) of the second protruding portion (134a, 1234a) is provided with a second trench structure (134c, 1234c) corresponding to the first tenon portion, and the first tenon portion of the impedance matching member is inserted into the second trench structure (134c, 1234c) of the field adjustment member (130, 1230); and an outer cover member (150, 1250), which comprises a first tapered structure (151, 1251) and a second tenon portion corresponding to the first trench structure (131a, 1231a), wherein the first tapered structure (151, 1251) comprises a vertex angle (A1, A2) and a bottom surface, the second tenon portion is connected to the bottom surface of the first tapered structure (151, 1251), and the second tenon portion of the outer cover member (150, 1250) is inserted into the first trench structure (131a, 1231a) of the field adjustment member (130, 1230). an impedance matching member comprising a first end and a second end opposite to each other, wherein the first end of the impedance matching member comprises a first tenon portion, and an end surface of the second end of the impedance matching member is provided with a first recessed structure, wherein the first recessed structure comprises a first protruding portion and a first groove structure surrounding the first protruding portion; a field adjustment member (130, 1230), which comprises a first end (131, 1231) and a second end (132, 1232) opposite to each other, wherein an end surface of the first end (131, 1231) of the field adjustment member (130, 1230) is provided with a first trench structure (131a, 1231a), and an end surface of the second end (132, 1232) of the field adjustment member (130, 1230) is provided with a second recessed structure (134, 1234), wherein the second recessed structure (134, 1234) comprises a second protruding portion (134a, 1234a) and a second groove structure (134b, 1234b) surrounding the second protruding portion (134a, 1234a), and a top surface (135, 1235) of the second protruding portion (134a, 1234a) is provided with a second trench structure (134c, 1234c) corresponding to the first tenon portion, and the first tenon portion of the impedance matching member is inserted into the second trench structure (134c, 1234c) of the field adjustment member (130, 1230); and an outer cover member (150, 1250), which comprises a first tapered structure (151, 1251) and a second tenon portion corresponding to the first trench structure (131a, 1231a), wherein the first tapered structure (151, 1251) comprises a vertex angle (A1, A2) and a bottom surface, the second tenon portion is connected to the bottom surface of the first tapered structure (151, 1251), and the second tenon portion of the outer cover member (150, 1250) is inserted into the first trench structure (131a, 1231a) of the field adjustment member (130, 1230).