In this paper, hydrogel membrane techniques used for CO2 removal from air were introduced. Firstly, the PVDF hollow fibers were prepared by dry-jet wet-spinning phase-inversion process, then membrane module was made of them as a CO2 removal equipment. PVDF hollow fiber membranes modified by alkali, was casted by PVA hydrogel on its surface and PVDF-PVA hydrogel membranes were prepared. The effects of the concentration of monomer (PVA) and cross-linker (glutaraldehyde) on the swelling ability of the gel of hydrogel membranes were investigated. For carbonate hydrogel membrane, CO2 concentration from 1.3% to 0.6% in feed gas could be decreased to 0.9-0.4% at the outlet at 25degreesC. For an immobilized enzyme hydrogel membrane, CO2 concentration from 0.7% to 0.5% in feed gas could be decreased 20% at 25degreesC.