Abstract: A door lock structure is proposed, including a chassis, a tongue mechanism, a latch mechanism, a security latch mechanism, a doorknob linking mechanism and a doorknob control mechanism, which is characterized in that a restriction member that restricts the relative motion between the linking member and the rotating member is installed between the rotating member connected with the doorknob and the linking member connected with the latch mechanism. The restriction member controls the doorknob to be linked or unlinked by means of a button, wherein an adjustment piece is formed at an edge of a transmission piece having a contact with the restriction member to adjust the doorknob to be located on inner side or outer side of the door. Also, a fireproof piece having a security function is disposed in the latch mechanism to prevent the door from opening in case of a fire hazard.