High-temperature (above 150 ℃) dolomite synthesis experiment was considered to be an effective way to understand the genesis of natural dolomites. Under the consideration of the Mg/Ca concentration index that has an important impact on the genesis of natural dolomites, our experiment used two kinds of aragonitic bioclasts (Acropora, Ficus) as the precursor reactants in the 220℃ conditions to study the dolomitization process under different Mg/Ca mole concentrations (0.5, 0.7, 1.0, 1.2, 1.5) and reactant time (0.5h, 1.0h, 1.5h, 2h, 3h, 6h, 8h, 14h) respectively. The results show that the dolomitization process under high temperature can be divided into induction stage, rapid reaction stage and stable stage. This reaction process was not obviously affected by the precursor aragonite reactants, implying that the Mg/Ca concentration should have an obvious influence on the dolomitized products. With the increase of Mg/Ca mole concentration in the reaction solution, the induction period of dolomitization was shortened and the rate of dolomitization was accelerated, with the reduced mole %CaCO3 (abbreviation as %Ca) and the increased order degree of the product dolomites, which should indicate that high Mg ion concentration could rapidly promote the replacement of Ca ions by Mg ions in aragonite lattice and complete the ordering process of the dolomites. The research results provide basic theoretical support for explaining the influence of Mg/Ca mole concentration on natural dolomitization process.