The invention discloses a direct-acting sealing device, and a circuit breaker and a gas-insulated switch cabinet using the same, and belongs to the technical field of air cabinet sealing devices. Thedirect-acting sealing device comprises a sleeve which is radially moved along a mounting hole of a sealing plate and is axially positioned and assembled on the sealing plate along the mounting hole ofthe sealing plate; a pull rod through hole in sliding seal fit with an insulating pull rod is arranged in the sleeve; the sleeve is provided with a sleeve stop piece in stop fit with the sealing plate in an axial direction of the mounting hole; the sleeve stop piece and the sleeve are in stop fit in the axis direction of the mounting hole, so that the sleeve can be axially positioned and assembled on the sealing plate along the mounting hole of the sealing plate; and the sleeve is sleeved with a mounting hole sealing ring hermetically assembled between the sleeve and the hole wall of the mounting hole of the sealing plate. According to the device, the sealing performance of an axial reciprocating motion of the insulating pull rod can be ensured, and the sealing performance during axial and radial run-out can be realized; and therefore, the problems that an existing metal corrugated pipe sealing technology is poor in dynamic sealing performance and easy in damage are solved.