Applicant discloses a new viewpoint and its application for the freshwater generation here: Air temperature exchanges between the inside and outside of the deserts always play an important role in the generation of freshwater in desert environment. Because this procedure is continually happening in days and nights, and the desert area is large in the world, so, the amount of the water production by this way is extent to which one could be imagined. According the viewpoint disclosed here, it will bring big benefits to take over the shortage water plight and for the development of the desert. According this doctrine, the easiest way to collect the water from the desert is just setting an impermeable layer under the dune: the fresh water should flow out. By use of artificial stacked large amount sands can also obtain the freshwater in anywhere which the changes of the temperature are big.