A hollow fiber adsorbent compressed dry air system including an intake unit, a first adsorption/regeneration unit, a second adsorption/regeneration unit, a switch unit and an exhaust unit is disclosed. The first adsorption/regeneration unit has a hollow fiber adsorbent housing and a heating device disposed in the surrounding of the adsorbent housing. The second adsorption/regeneration unit has another hollow fiber adsorbent housing and another heating device disposed in the surrounding of the another adsorbent housing. One of the hollow fiber adsorbent housings performs drying procedure to the compressed air in the room temperature, and the other hollow fiber adsorbent housing, when heated by the heating device thereof, performs a desorption regeneration procedure in a high temperature condition. The switch unit alternately switches the drying procedure and the desorption regeneration procedure to the first adsorption/regeneration unit and the second adsorption/regeneration unit. The exhaust unit outputs dried product air.