A door lock includes a main part including an axial tube and a connection tube extending on two ends thereof. A mounting plate has a mounting hole and at least one first engaging portion. A first plate has at least one second engaging portion which faces the mounting plate. Multiple first fixing members extend through the first plate and are not connected to the mounting plate. A second plate is mounted to the connection tube and includes multiple positioning holes. Multiple fastening members extend through the positioning holes and are connected to the first fixing members. The second connection portion is threadedly connected to the first connection portion to adjust a distance between the mounting plate and the main part so that the door lock can be installed to doors of different thicknesses.