Abstract: We made in this paper a brief review on the history of exploration for large gas fields in the Sinian and Cambrian in the Sichuan Basin of the Upper Yangtze Platform, and concluded that the Moxi-Longwangmiao Gas Field is the oldest and largest gas field ever found so far in China within the past 5 years. The success of exploration is owing to the discovery of the Mianyang-Changning Aulacogen. Then we further elaborated the tectonic location, boundary conditions; hydrocarbon generation, reservoir properties, and formation and evolution of hydrocarbon accumulations in the aulacogen. The theoretical and practical researches of the fields are beneficial and helpful to the comparative study of hydrocarbon accumulations in the Lower Yangtze Platform or the South Yellow Sea Basin.