Improvement of an air revitalization technology is one of the key elements for ECLSS (Environment Control and Life Support System) in development and operation of human space systems. The paper summarizes, as a validation of off-gases “removal” technique, the actual 24hr-continuous operation testing under closed environment. The analysis focuses on the removal characteristics with low CO2 (Carbon Dioxide) concentration. A preliminary closed-loop test of CO2 “reduction” technique was conducted as well. The evaluation includes the data acquisition and analysis of CO2 Reduction Processor which employ Sabatier-reaction and air-cooling. And finally the paper addresses the key issues to further improve this air revitalization system.