A fast clutch mechanism for an industrial door is provided. A worm is connected to a motor shaft of the industrial door and meshes with a worm wheel which is rotatably mounted on an output shaft of a transmission box. The fast clutch mechanism includes: a clutch sleeve surrounding the output shaft and restricted to be slid axially on the shaft, one end of the sleeve being capable of engaging a corresponding surface of the worm wheel, while the other end having a ring portion extended outwardly; a rotation device including a rotation shaft and a rotation actuating device coupled with one end of the rotation shaft; bevel gear driving device which includes a primary bevel gear mounted on the rotation shaft and a secondary bevel gear engaging with the primary bevel gear; a differential device including a drive gear rotatable with the secondary bevel gear, two follower gears engaging with the drive gear, and two cam shift levers connecting respectively the two follower gears in an axial direction, the two cam shift levers resisting against the ring portion of the clutch sleeve so as to make the clutch sleeve slide between an engagement position and an disengagement position with the clutch assembly. The present invention has the advantage of realizing ease clutch operation on the ground, thus reducing potential dangers.