Automatic locking mechanism and electric heavy truck

The invention relates to an automatic locking mechanism and an electric heavy truck, and belongs to the field of electric heavy truck battery replacement. According to the scheme, the locking device comprises a locking fixing support and a locking fixing buckle, the locking fixing buckle comprises a rotating part with one end hinged to the locking fixing support and a locking end fixed to the rotating part and used for locking a battery box when the locking end is pressed downwards, and the other end of the rotating part is hinged to one end of a supporting part of a locking rotating piece; the other end of the supporting part is hinged to one end of a locking self-locking piece, and the other end of the locking self-locking piece is hinged to the middle position of the locking fixing support. A pulling part is further arranged on the supporting part, and one end, far away from the supporting part, of the pulling part is connected with a push-pull device for locking and unlocking the battery box; when the loc