This paper, based on observing and measuring the field section, the thin section analysis, cathodoluminescence analysis, particle size analysis, scanning electron microscope analysis, andenergy spectrum analysis, has studied sedimentology characteristics of eolian sandstones in the Lower Cretaceous Mangang Formation, in the Jinggu area, Simao Basin, Yunnan, and then, and the paleoclimate significance of eolian sandstones of this area. This paper has summarized the development characteristics of eolian sandstones. The purpose of this article is to provide some base dates for further studies of the paleoclimate significance of eolian sandstones. And meanwhile, it may be open up a new way of thinking for explorations of potash resources. It shows as follows: ① The lithology of eolian sandstones of this area is mainly middle fine lithic quartz sandstone and quartz sandstones. In this area, it developed middle large scales cross bedding, parallel bedding. The sorting of grains is medium to well, and the psephicity is sub round to round, and the pores do not develop, and the content of matrix is low. ② The grains of quartz sandstones, which shows parallel bedding in the middle member of the Mangang Formation, is perfectly round and has two modal scores. There are some features of the particle surface, such as dish pits, which is the typical chareacteristics of eolian sandstones. According to this, it can be speculated that the sedimentary environment was eolian sand dunes and eolian indunes. ③ During the process of the transportation, the sedimentation and the diagenesis, it underwent a setting of dry warm climate in in the Mangang Formation, Lower Cretaceous, in Jinggu area. The sedimentary environment of the middle member of the Mangang Formation was the eolian interdune deposition, while the sedimentary environment of the upper member and the lower member of the Mangang Formation were the eolian dune deposition. The formation of eolian sandstones experienced long physical weathering and chemical weathering. During those processes, it had been in oxidation environments, and the wind strength was strong as a stable speed. In addition, it probably experienced a period of time of humid climate environment. And it was probably related to meteoric waters, the migration of atmospheric circulation zones and the progress of transgression during the Cretaceous.