The heatless regeneration adsorption dryer is a kind of equipment for drying the compressed air according to the principle of pressure swing adsorption. It absorbs the moisture in the compressed air under pressure, so that the compressed air can be dried. When the pressure is reduced, a part of the dry compressed air is used to purge the adsorbent for regeneration, and the two towers alternate with each other, so that the dry compressed air can be recycled. According to the pressure dew point of the compressed air Different adsorbents are selected. The commonly used adsorbents are activated alumina and molecular sieve.