A quick-positioning captive screw includes a mounting base member having an outer thread spirally extending around the peripheral wall of a top flange thereof, the outer thread having a leading end terminating in the top edge of the top flange and a tail end terminating in the bottom edge of the top flange and cutting a part of the top flange into a rib, a lock screw having an inner thread located on the inside wall of a plastic cap thereof for threading through the outer thread into the space around the periphery of the mounting base member below the bottom edge of the top flange after bonding of the mounting base member to an external panel frame by reflow soldering, and a spring member sleeved onto the threaded shank of the screw bolt of the lock screw and stopped between the head of the screw bolt and the inside step of the mounting base member.