Quartz sand grains have a variety of surface characteristics, which could be used as the main indicators of their depositional environment. In the present study, the surface characteristics of quartz sand grains were systematically analyzed on the basis of the samples from varying levels of the Baoxiangsi Formation in Lijiang-Jianchuan area, Yunnan Province, by using electronic scan microscope. The results show that the grain surfaces of the samples have aqueous characteristics, those from the middle part have eolian characteristics. It is thus concluded that the lower part is a proximal diluvial environment, the middle part is an eolian dune environment, and the upper part is a lake environment.