The invention provides an ultra-wideband high-gain yagi antenna. The ultra-wideband high-gain yagi antenna comprises a wideband folded dipole exciting unit, a one-to-two micro-strip power divider, a first directing unit and a reflecting plate; the wideband folded dipole exciting unit is of a rectangular frame structure formed by bending a conductor sheet, the middle of the long edge of one side of the rectangular frame is broken to form a feed clearance, and the height of the two ends of the portion, located at the feed clearance, of the conductor sheet is gradually decreased, so that a conical pin structure is formed; the input end of the one-to-two micro-strip power divider is far away from the wideband folded dipole exciting unit, and the two output ends of the one-to-two micro-strip power divider are connected with the two ends of the feed clearance of the wideband folded dipole exciting unit through metal posts respectively; the first directing unit is a half-wave dipole, is arranged on one side of the wideband folded dipole exciting unit in the height direction and is parallel to the wideband folded dipole exciting unit; the reflecting plate is arranged on the other side of the wideband folded dipole exciting unit in the height direction and is parallel to the wideband folded dipole exciting unit. According to the ultra-wideband high-gain yagi antenna, the wideband folded dipole exciting unit adopts a double-feeding point scheme to achieve high gain, and the folded dipole is adopted, so that large bandwidth and good matching are achieved.