Abstract: The present apparatus provides an adjustable key-type spring pin lock cylinder. The spring pin lock cylinder includes a lock core (1), a first core sleeve (2), and a second core sleeve (3). At the rear section of the lock core, two depressions, each with a countersink on one side, are made. Two steel balls (4) are respectively placed into the depressions. On the rear cover (5) of the lock, there are two through-holes in which the press rods (6) and the springs (7) are placed. By turning the adjusting lever (10) on the supporting stand (9), either key may be selected to open the lock or only one of the two keys can open the lock.