A series of experimental tests using NORDTEST method for evaluating the moisture buffering capacity of different porous hygroscopic materials have been carried out in the Yangtse River downstream area (Nanjing for example),. The impact of MBV on building energy consumption and indoor humidity has also been investigated. The test results show that the MBV of porous hygroscopic materials is larger under higher humidity range, and there was obvious difference when using diverse materials. Research indicates that it may be possible to reduce up to 10% cooling energy consumption in the Yangtse River downstream area(hot and humid climate) in China, when applying hygroscopic materials with well-controlled HVAC systems. Meanwhile the indoor humidity can also be modulated to a certain extent.