A device for locking and unlocking a ball valve through a cipher belongs to the technical field of ball valve locks for water pipeline sealing. The device is arranged above a ball valve seat; a locking valve rod is arranged in a stepped hole vertically arranged in the front of the lower part of a lock. The lower end of the locking valve rod extends into two round nests above the valve seat. A slide block is pressed on the upper end of the locking valve rod; and the rear end of the slide block is supported by the front end of a telescopic rod. The front end of a telescopic rod spring is supported behind a square panel of the telescopic rod; and the other end of the telescopic rod spring is supported at the front end of a cipher sheath. The external circle of the cipher sheath penetrates into a central hole of the cipher sheath to be fixedly connected. A plurality of through open slots at the inner circle of the cipher sheath are sleeved at a boss of the telescopic rod. A plurality of cipher wheels are placed into the plurality of open slots arranged at the middle and rear positions of the lower part of the lock. The plurality of through open slots arranged at the middle and rear positions of the upper part of the lock are fastened on the external circle of plurality of cipher wheels arranged at the middle and rear positions of the lower part of the lock. The connecting parts of the upper part and the lower part of the lock are fixedly connected. The device is convenient to use, needs no key, and is used for locking and unlocking the ball valve through thecipher.