Abstract: Badain Jirin sandy desert is the second largest sand desert in China,it covers 49,200 Sq. km. It formed at least as early as middle-Pleistocene and underwent changed processes of development and fixation with the influence of climate changed during glacial and interglacial epoch. The megadunes were formed by winds during the long changed processes and it was also the main factor for the cause of formation and evolution of the salt lakes which inter-distributed between the megadunes.