The invention relates to a locking device. The locking device comprises a fixed bracket, an operation piece and a locking piece, wherein the fixed bracket is fixedly connected to the edge of a packingbox; the operation piece comprises a hinge end, and an operation end relative to the hinge end; the hinge end is connected to the fixed bracket in a manner of rotating around a first axis; the locking piece comprises a connecting end, and a locking end relative to the connecting end; the connecting end is connected to the operation piece in a manner of rotating around a second axis; the locking piece is rotationally connected to a connecting point of the operation piece between the hinge end and the operation end; the process of rotating the operation piece around the first axis comprises a connecting position; and when the operation piece is rotated to the connecting position around the first axis in a preset direction, the locking end of the locking piece can be connected with a packingbox cover. Through linkage cooperation of the operation piece and the locking piece, the locking device realizes locking between the packing box cover and the packing box. A cam or a spring is prevented; the wear of each part in long-time use process is lower; the looseness phenomenon is not easy to occur; the locking stability is improved; and the service life is prolonged.