The invention discloses a locking device for a tobacco transport box and relates to a clamping device for fixing or maintaining a sealing piece. The locking device comprises a clamping device and further comprises a transmission unit and a mounting unit. The transmission unit comprises a fixing plate, a locking plate, a rotating disc and a transmission piece with the 8-shaped outer contour. A straight-line sliding groove is formed in the fixing plate, the locking plate is arranged in the sliding groove, and a working cavity is formed in the locking plate. The rotating disc is arranged in the fixing plate, a rotating lock is arranged at one end of the rotating disc, a pin shaft is arranged at the other end of the rotating disc and connected with the upper end of the transmission piece, andthe transmission piece is movably arranged in the working cavity of the locking plate. The clamping device is arranged at the upper end of the locking plate, and the mounting unit is arranged at the lower end of the fixing plate. The locking device has the beneficial effects that a box cover and transport hoisting design are integrated, and thus the mounting cost is reduced; special eccentric camdesign and self-locking design are adopted, and the stability of the whole fixture is guaranteed; and the locking device is compact in whole structural design, convenient to use, and worth popularizing.