The Dianjiang depression of eastern Sichuan basin is one of the most important salt basins in the Triassic. However, there exist some disputes about whether the paleo- brine reached potash deposition and whether preferential metallogenic conditions for marine potash formed. In this paper, we carried out chemical analysis for salt samples from Changping well 3, Gaotan well 1, and ZK001 Jialingjiang Formation in the Dianjiang depression, and chlorine isotopic analysis for the salt samples from Changping well 3 to determine depositional stage of paleobrine and formation condition. The results indicate that all chlorine isotopic values o the Triassic Jialingjiang halite are negative, lower than -0.32‰, with the lowest value of -1.18‰, and most Br/Cl ratios are higher than 0.31, with coefficient of bromine chloride in some samples exceeding 0.45. There features imply that during the Jialingjiang period paleo- brine in the Dianjiang depression had reached the precipitation stage of sylvinites, which is consistent to analysis result of inclusions in halite. Combined with analysis of climate, provenance and tectonic factors, it can be concluded that the Dianjiang depression was hot, abundant in potash source, existence of sub-depression, and excellent tectonic condition, all of which determined the great potential for the formation of marine potash.