Based on the studies of microfossils (including phytodebris and acritarchs) and large stout tubular trace fossils, the upper part of the originally defined Huixingshao Formation in the Xiushan area, Chongqing city, is recognized the Ludlow-Pridoli Xiaoxi Formation. The original Huixingshao Formation is revised, and subdivided into two parts, the upper part being the Xiaoxi Formation and the lower part being the Huixingshao Formation. The geological age of the redefined Huixingshao Formation is late Telychian of the Llandovery. A survey of Ludlow-Pridoli strata in the Yinjiang area of Guizhou Province, Xiushan area of Chongqing City, and Longshan-Zhangjiajie area of Hunan Province shows that, after the “Yangtze Uplift”, Ludlow-Pridoli strata were deposited the interior of the Yangtze Platform from the Zhangjiajie area of Hunan Province to the Yinjiang area of Guizhou Province, suggesting that the Yangtze Platform was flooded by shallow seawater in Late Silurian.