Salt lake lithium in Qaidam Basin takes 80% brine lithium resource of China, mainly distributed in four salt lakes of Bieletan, Yiliping, Dongtaijinaier, and Xitaijinaier. This paper studied the lithium minerogenesis causes because there were many discrepancies on the issue before the 1980s. The results show that content Li ⁺ in surface brine is controlled by Li⁺ in inflows and is positively related to Li⁺ in underground water. Based on calculations on monitoring water discharge and estimating Li⁺ contents in Hongshui and Nalinggele Rivers, it was lasted about server thousand years when the four salt lakes experienced strong evaporation and caused lithium concentrated. Hongshui River inflow sourced from hot springs associated with Cenozoic volcanic activities along the Kunnan deep fault, which is the brine lithium source possibly. Lithium resource and distribution in the four salt lakes depended on the changes in the water system.