A quick-releasable nail output nozzle for a nail gun includes a nozzle base, which is affixed to a nail outlet port of a nail magazine and has a nail output groove on the front side for guiding out a bar of nails, two side wings, and two hooks spaced below the side wings. A nozzle cover is covered on the front side of the nozzle base and has two flanges with protruding blocks respectively hooked on the back side of the side wings of the nozzle base. A locking lever is pivoted to the nozzle cover. A hook rod is pivoted to the locking lever for hooking up with the hooks of the nozzle base by means of the control of the locking lever.