Abstract: The environmental control and life support system (ECLSS) for a manned space craft is quite different from that for all unmanned spacecraft, with the cabin air temperature and humidity control (THC) as a key part. Taking the US cabin as an example, the paper reviews the scenarios of each cabin THC onboard the ISS, including the design indices, the buildup of the hardware and the techniques adopted. The key techniques of the THC onboard the ISS are discussed, including the condensing heat exchanger (CHX), and its internal mechanisms ofthe heat eliminating and the vapor condensing. With a new type porous media CHX ofNASA in mind, the paper comments on the development direction ofthe future CHX.