Evaporative cooling medium

The invention discloses an evaporative cooling medium. A first component consists of any one or any combination of two or three of dodecafluorohexanone, dodecafluorohexane and dodecafluorohexene; a second component, which is contained or not contained, is selected from any one or any combination of two or three of fluorine-containing alkane, fluorine-containing olefin, fluorine-containing ketone and fluorine-containing ether. The evaporative cooling medium cannot damage the ozone sphere, and is safe and environment-friendly as well as good in evaporative cooling effect; the evaporative cooling medium is specifically applicable to a thermal power generation set, a wind power generation set and a hydro electric generating set.