The invention relates to a locking device, in particular to a locking device of a self-unloading vehicle container. The device comprises the container, a container back cover, a vehicle rack, a back cover blocking part, a connection rod rack, a push-pull connection rod and a hydraulic cylinder, the upper left end of the container back cover is hinged to the upper right end of the container througha first hinged shaft, and the vehicle rack is hinged to the lower right end of the container; the middle end of the back cover blocking part is hinged onto the vehicle rack, the upper end of the backcover blocking part is located at the right end of the container back cover, and the lower end of the back cover blocking part is hinged to one end of the push-pull connection rod; the other end of the push-pull connection rod is hinged onto the connection rod rack, the connection rod rack is fixedly connected to the lower end of the container, and the lower end of the hydraulic cylinder is hinged onto the vehicle rack. The locking device of the self-unloading vehicle container has the advantages that the container back cover can be automatically opened along with the aslant linkage of the container, accordingly the container back cover can be prevented from being opened automatically, when the inclined angle of the container is large enough, the container back cover is opened, and the device is beneficial for unloading of the cargo.