Boron is a strategically important non- metallic mineral in China, widely used in high- tech fields such as new energy, advanced materials, and electronic information. Salt lake- type borate deposits, mainly distributed across the Qinghai- Tibetan Plateau, represent the most important and promising boron resource type in the country. Boron- rich salt lakes on the plateau show hydrochemical zonation, with variations in borate deposit types across different hydrochemical environments from south to north. However, comparative studies of boron- rich salt lakes in these different zones remain limited. This paper summarizes and compares the sedimentary characteristics of solid boron deposits and the geochemical parameter differences of boron- rich brines among three types of salt lakes on the Qinghai- Tibetan Plateau: carbonate type (zone Ⅰ), sodium sulfate subtype- magnesium sulfate subtype (zone Ⅱ), and magnesium sulfate subtype- chloride type (zone Ⅲ). The main conclusions are obtained as follows: ① Borate minerals are mostly deposited directly on top of the clastic sediments and present interactive multilayer deposition characteristics, indicating that borate deposition requires brackish water recharge and hydrological fluctuations, which accords with the theory of “brine diluted into salt”. ② The deposition of borax and ulexite is closely associated with abundant mirabilite, whereas pinnoite and kurnakovite deposition is accompanied by a large number of magnesium- bearing carbonate minerals (e.g., hydromagnesite and dolomite). This indicates that borax ulexite formation depends on Na+- rich water recharge, while pinnoite and kurnakovite precipitation requires Mg2+- rich inflows. ③ The boron precipitation thresholds in zones Ⅰ, Ⅱ, and Ⅲ are similar, with brine pH>8 and B content exceeding 400 mg/L. However, notable differences exist in total dissolved solids (TDS), Mg, and Na content among the lakes. ④ B×10- Na- Mg ternary equivalent diagram, combined with borate deposit chemistry, reveals that Na and B equivalents in zones Ⅰ~Ⅲ range between 0. 2~0. 6 and 0. 4~0. 7, respectively. In contrast, Mg equivalence varies: zone Ⅰ values remain below 0.1, while zones Ⅱ and Ⅲ range between 0. 1 and 0. 4.