Abstract: We make the content of Boron and the ratio of Sr/Ba、Sr/Ca the target，and calculate the palaeosalinity values
of sedimentation epoch in Sha 4 of the south slope in Dongying Depression. The palaeosalinity in vertical direction totally
decreases from down to up. The palaeosalinity is higher in early stage of lake invading and becomes lower in later stage. The
east is relatively higher in plane and the north is lower. The distribution of palaeosalinity is controlled by palaeowater-depth.
The palaeosalinity controls different types of carbonate rock and the palaeosalinity limits is in 10.0 ‰ 35.0 ‰. The dolomite is
mainly distributed in the area with palaeosalinity higher than 15.0 ‰ while the limestone is mainly distributes in the area lower
than 20.0 ‰. The high salinity of water supplies the material base and media condition for the dolomite formation and dolomitic
diagenetic change. In the area of high salinity the the primary deposition is dolomite，or formed limestone the dolomitisation，
the limestone deposition is primary in the area of low salinity.

Key words: palaeosalinity, brackish water, dolomite, limestone, controlling action