Objectives: The Xiuning Formation in the North Jiangxi Province and the Liantuo Formation in the Yichang and Tongshan areas, Hubei Province, are two important stratigraphic units of the middle Neoproterozoic in the Yangtze Block. However, there have been controversies on the sedimentary geotectonic settings and depositional interval. Combined with field sedimentary survey and the LA-ICP-MS U-Pb dating of the sandstone and tuff of the Liantuo Formation, we analyzed the deposition interval and tectonic properties of the Liantuo Formation. Methods: On the basis of detailed regional sedimentological and regional comparative study, LA-ICP-MS zircon UPb dating has been carried out for gravel-bearing sandstone and sedimentary tuff from the bottom and middle of the Liantuo Formation in Shimentang section, Tongshan County, and the dacite from the top of the Shangshu Formation and sedimentary tuff from the middle Xiuning Formation in the Ganling section, Huatan, Shangrao City, respectively. Results: The maximum deposition age of the Liantuo Formation is 784.0 ± 11 Ma, the middle Liantuo Formation is 728.7 ± 9.6 Ma in the Shimentang section, and the dacite from the topmost of the Shangshu Formation is 779.0 ± 6.6 Ma, the middle Liantuo Formation is 733.6 ± 5.9 Ma in the Ganling section, respectively. The sedimentological investigation shows that the sedimentary structure of the Xiuning Formation in the Ganling section is not developed. Instead, they are represented by deposited facies from alluvial fan—shallow-water shelf—deep-water shelf. The sedimentary structures of the Liantuo Formation in Tongshan County are developed, such as diagonal bedding, cross bedding, sand cross lamination and ripples, which are indicative of coastal to shallow shelf depositional settings. Coclusions: Based on previous research results, therefore, the deposition interval of the Liantuo Formation or the Xiuning Formation in northern Jiangxi and its adjacent areas is constrained to be about 780 ~ 720 Ma. The regional comparative study shows that in the Yangtze Block, the Liantuo Formation (the Xiuning Formation) in the northern Jiangxi Province and its adjacent areas, and the Chengjiang Formation in central Yunnan Province, and the upper Banxi Group in Hunan, Guizhou and Guangxi areas are simultaneous heterogeneous deposition sequences, which is the first set of rifting cover deposits in the Nanhua Rift system under the settings of regional thermal subsidence before the onset of the first Neoproterozoic glaciation.