Lacustrine dolomite has received considerable attention during the last twenty years due to its scientific and high economic value in conventional and unconventional hydrocarbon reservoirs. Compilation of lacustrine dolomite in deep time can help to clarify the hydrochemical conditions in which dolomite was formed. In deep time, lacustrine dolomite facies can be divided into two categories: i) lake-marginal facies including dolograinstones and dolomicrobialites, and ii) lake-central facies comprising alternated dolomitic mudrocks/argillaceous dolomites, tuffaceous dolomites/dolomitic tuffites, analcimic/albitic dolomites/dolomitic analcimolites, as well as dolomitic sandstones. Based on lake water salinity and alkalinity, ancient dolomite-rich lakes can be genetically classified into four types: non-alkaline (pH < 9) brackish, non-alkaline saline, alkaline (pH > 9) brackish, and alkaline saline lakes. Dolomites in different lakes show distinctive features in lithofacies, minerology and isotopic compositions (carbon and oxygen). The formation of early dolomite (primary and early diagenetic dolomite) in different lacustrine depositional systems coincidentally resulted from a significant increase of Mg2+ concentrations and alkalinity in bulk lake water and/or porewater. The Mg2+ increment might be due to climate-controlled intense evaporation and/or by excessive input of Mg2+ from hydrothermal fluids and/or basic volcanic tuffs into brackish lakes which increases alkalinity with subsequently precipitation of dolomite. Moderately positive carbon isotopes (delta C-13 = +2 to +10 parts per thousand, V-PDB) and negative oxygen isotopes (delta O-18 = 0 to -20 parts per thousand, V-PDB) are indicative, not exclusively, of such hydrothermal- or volcanic-related lacustrine dolomite. In alkaline water systems, dolomite can be dominantly primary in origins and the presence of preexisting Ca-carbonate minerals is not very important for dolomite enrichment in deep time.