The late-Sinian(Ediacaran) to early-Cambrian intracratonic rift in central Sichuan basin has a close relationship with the formation of Anyue Sinian(Ediacaran)—Cambrian giant gas field. geochronology study of the Dengying Formation is significant in understanding the evolution of the intracratonic rift. LA-ICP-MS U-Pb analysis of volcanic ash beds in the Third Member of the Dengying Formation at the Xianfeng Section, Sichuan, Southwest China yield a highly reliable Concordia age of 539.6±1.4 Ma(MSWD=0.22), suggesting a lower placement of the Precambrian—Cambrian boundary in the Sichuan Basin. We eatablished a evolution time frame of this intracratonic rift based on four isochronous strata, the bottom of the Dengying Formation(551.1 Ma), the Third Member of Dengying Formation(539.6 Ma), the Maidiping Formation(535.2 Ma) and the Ni—Mo sulfide enriched layer in the lower Cambrian(521 Ma). The boundary of the Maidiping Formation and the Dengying Formation inside and outside the rift is not synchronous. According to those, we propose that the formation of the lateSinian(Ediacaran) to early-Cambrian intracratonic rift in central Sichuan Basin was mainly controlled by the boundary fault. Due to the deep-water depositional environment in the rift, the Maidiping Formation began to deposit rapidly after the deposition of the thin Third and Fourth Member of the Dengying Formation, the Maidiping Formation and the Qiongzusi Formation inside the rift and the Fourth Member of the Dengying Formation outside the rift are contemporary heteropical sediments.