The invention discloses a coded lock cylinder system with a variable tooth profile, and belongs to the technical field of locks. A user-defined code area is arranged on a key, and a code setting area capable of adjusting billiard length is arranged on the corresponding lock cylinder, so that a user can set or change the key code combination, and modify the corresponding billiard length in the lock cylinder so as to be correspond to the key newly set by the user, and thus the user can set the key and the lock cylinder codes according to own requirement and does not need to replace the lock cylinder after the key is lost, the labor and material costs are reduced, and the property and personal safety risks are also reduced. In addition, the coded lock cylinder system with the variable tooth profile adopts the manner of combination of a transmission ring and an operating button, when the key is inserted into a key hole, no action is permitted, and only the operating button at the bottom of the lock cylinder is used for operating the lock cylinder shift fork to control a master lock body on a security door or other devices to act, so that various ways of traditional cracking cannot be achieved by impacting and shaking the buttons or the key, and thus the safety of the lock cylinder is ensured.