The security of colored paintings has been seriously threatened by a large amount of condensed water on the frescos in two Southern Tang dynasty cemeteries as the seasons change. Data obtained from July to August in 2013 indicated that the temperature and humidity in the tombs are continually 22 ℃ and 100%, respectively. Based on this investigation and survey, a new method to control condensed water by using air curtains and dehumidifiers was proposed. As a result, the humidity indoor was reduced from 100% to 90%. In this case, the condensed water on the frescos is effectively controlled.