The invention discloses a gas separation method using sub-pressure swing adsorption, wherein the method comprises pretreatment, negative pressure adsorption concentration, refinement, and recovery removal. According to the present invention, based on pressure swing adsorption, different material components have different adsorption separation coefficients and different physicochemical properties under a negative pressure, adsorption is performed under the negative pressure, evacuation or rinsing desorption is performed, and various separation methods are coupled, such that various mixed gasesare separated and purified through the circulation operation of the pressure swing adsorption process, and particularly the relatively easily adsorbed (and relatively difficultly desorbed) component is separated and purified, wherein the adsorption and the desorption in the circulation are easily matched and balanced; the generated non-adsorbed gas is the intermediate gas, or is the product gas and the qualified discharge gas, or enters the subsequent refining process so as to be refined to obtain the product gas or the qualified discharge gas; and the generated desorbed gas is the condensed gas, and sequentially enters the subsequent recovery removal process so as to further recover or remove the adsorbate component.