A bushing for conducting air in a nail gun is arranged between an air chamber and a cylinder received in a housing of the nail gun. The bushing is adjacent to a bottom of a main valve for driving hitting motion of the nail gun. A number of main valve holes that are adjacent to the main valve are formed in a sidewall of the cylinder. At least one air inlet is formed in a bottom of a sidewall of the cylinder. An air flow passage is defined in the housing and is in communication with the main valve and the air hole. A valve plug which is configured for opening or closing the air flow passage is received in the air flow passage. The valve plug divides the air flow passage into an upper portion and a lower portion. The lower portion is formed in the housing. An annular end surface is formed on a top of the bushing. The annular end surface defines a main air inlet for the main valve. An end portion extends from the bushing and having the upper portion of the air flow passage formed therein. The bushing further includes at least one upper air hole in communication with the air chamber, the main inlet and the upper portion of the air flow passage.