The invention discloses a swing-type diameter-variable envelope forming full-section drill tool, which comprises a swing mechanism, a drill arm, driving devices and a drill tool body. The swing mechanism comprises an outer shell, a first hydraulic cylinder, a second hydraulic cylinder, a third hydraulic cylinder and a fourth hydraulic cylinder, a transmission shaft coaxial with the outer shell ismounted in the outer shell, the upper part and the lower part of the transmission shaft are connected with the inner wall of the outer shell through bearings correspondingly, the lower part of the transmission shaft stretches out of the outer shell, a connecting plate is mounted on the part, outside the outer shell, of the transmission shaft in a sleeving mode, the first hydraulic cylinder and thesecond hydraulic cylinder are rotationally connected to a rack of a shaft tunneling machine in a splayed mode, the ends of piston rods of the first hydraulic cylinder and the second hydraulic cylinder are rotationally connected to the connecting plate, the third hydraulic cylinder and the fourth hydraulic cylinder are rotationally connected to the outer end of the connecting plate in a splayed mode, and the ends of piston rods of the third hydraulic cylinder and the fourth hydraulic cylinder are rotationally connected to the drill arm; and the drill arm is of a telescopic structure, the multiple driving devices are mounted at the end of the drill arm, and each driving device is connected with the drill tool body located below the drill arm. The swing-type diameter-variable envelope forming full-section drill tool can be suitable for different geological conditions, and full-section tunneling is achieved.