Relationship between hydrochemistry (Mg2+, Ca2+, Sr2+, Sr/Ca and Mg/Ca) and salinity of more than four hundred lakes in the Qinghai-Tibetan Plateau were analyzed. And its variation characteristics (differing from different sampling place and time, as well as Natural Evaporation) were also discussed. Mg2+ showed a stable positive relationship with salinity in lakes in the Qinghai-Tibetan Plateau. While Ca2+, Sr2+, Sr/Ca and Mg/Ca showed poor and unstable relationship with salinity. In water type specified lakes, however, it differed remarkably from different water type lakes. No clear relationship observed between Mg2+, Ca2+ and Mg/Ca and salinity in carbonate type lakes. Mg2+ showed positive relationship with salinity in sulphate type lakes, and Ca2+ and Mg/Ca remained poor relationship with salinity. While in chloride type lakes, Mg2+ showed distinct positive relationship with salinity, and Ca2+ also showed positive relationship to some extent with salinity. Mg/Ca still showed no clear relationship with salinity. In a single lake, Ca2+ and Mg/Ca still showed unstable and/or poor relationship with salinity, while Mg2+ still kept remarkable positive relationship with salinity. It was concluded that Mg2+ is a useful indicator for paleosalinity reconstruction in the Qinghai-Tibetan Plateau. Care should be taken while use Mg/Ca in recovering paleoenvironment and paleoclimate.