The invention discloses a trigger knife. The trigger knife includes a knife body, a knife holder, a blade, an elastic member, a trigger, a transmission mechanism and a block. The knife holder and the knife body are slidably connected, the blade is connected to the knife holder, and the elastic member is used for The blade provides an elastic force to be retracted into the inner chamber of the knife body, and the trigger is rotatably arranged on the knife body, so that the trigger can move in the knife body, and its part is exposed to the knife body. The transmission mechanism includes a first rack, a first gear, a second Two gears and a second rack, the first gear and the second gear are pivotally connected with the knife body, the central axis of the rotating shaft is perpendicular to the sliding direction of the tool holder, the first rack is arranged on the trigger and meshes with the first gear, and the second gear is engaged with the first gear. The second rack is arranged on the tool holder and meshes with the second gear, and the extension direction of the second rack is the same as the sliding direction of the tool holder; the tool holder is provided with a groove, and the extension direction of the groove is the same as the extension direction of the tool holder. When the blade is extended into place, the stop abuts against the wall of the groove. The trigger knife is easy to cut and has a longer distance.