The invention discloses a locomotive vehicle, a coupler and a coupler knuckle. A coupler lock comprises a coupler lock head, a coupler lock tail and a guide table, wherein the coupler lock head comprises a coupler lock top face, a coupler lock bottom face, a first side end face and a second side end face, the coupler lock top face is provided with a first side wall and a second side wall, the bottom face of the first side wall is provided with a first auxiliary locking face cooperating with a locking face of pushing iron, the bottom face of the second side wall is provided with a second auxiliary locking face cooperating with the locking face of pushing iron, the first side end face is provided with a main locking table, the bottom face of the main locking table is provided with a main locking face cooperating with the locking face of the coupler knuckle, and the distance between the main locking face and the coupler lock bottom face is greater than 0. By moving the position of the main locking face upward, the position of the locking face of the coupler knuckle can be moved upward so as to stagger the stress-bearing part of a lower traction table and reduce the stress, thereby prolonging the service life of the coupler knuckle.