By the study of the chronostratigraphy of the Mesoproterozoic Kunyang Group, we set a series of SHRIMP UPb dating has been achieved from the Liubatang Formation. According to the relationship of the depositional succession between the Neoproterozoic Liubatang Formation and underlying Mesoproterozoic strata, such as the Meidang, Dalongkou and Fuliangpeng formations and their chronostratigrphic data, we first set up new Systemic unit of the Yuxi system in Eastern Yunnan and fill up the position of the undefined (or unnamed) system in Chinese stratigraphic column. The authors did more field work in Yunnan Province and take the correlation of the isotopic zircon dating in the Kunyang Group. We consider the long term arguer of the “eight reverse order” is the true sequences of the Meso and Neoproterozoic strata in southwestern margin of the South China Croton. On the basses of the true sequence and combine the Yunxi System (1.2 ~ 1.0 Ga) with the Xishan System (1.4 ~ 1.2 Ga) which had been set up in North China Croton, we consider that the new system fill up the hiatus in the stratigraphic column of China.