The invention relates to a synthesis method of Estolides ester. The method comprises the following steps: taking oleic acid as a raw material, carrying out interesterfication reaction under the catalysis of a modified montmorillonite loaded methane sulfonic acid catalyst, adding a molecular weight regulator to regulate the polymerization reaction to obtain Estolides; and carrying out end-capping esterification of fatty acid by adopting alkyl chain fatty alcohol to obtain the Estolides ester. The Estolides ester obtained by the method disclosed by the invention has excellent low temperature performance and excellent lubrication performance; compared with other lubrication base oils and additives, the Estolides ester is a plant-based degradable and environmentally-friendly ecological lubricating material. According to the synthesis method disclosed by the invention, no highly corrosive acids such as perchloric acid, concentrated sulfuric acid and the like are used as an lnteresterification catalyst, so that the problems of multiple side reactions, difficult separation of by-products, deep product color, difficulty in removing the color and the like are effectively avoided; accordingto the method disclosed by the invention, the used methane sulfonic acid loaded catalyst has the advantages that mild corrosion is small, the reaction catalyst is easy to be separated from the product, improvements on benefits are facilitated and the production cost is reduced.