Preparation method of fumaric acid monoester

The invention belongs to the technical field of biochemical engineering, and particularly relates to a preparation method of fumaric acid monoester. Compared with the prior art, in the step S1, the immobilized lipase is used as a catalyst for transesterification reaction, the maleic acid monoester is synthesized by adopting an enzymic method, and the yield of the maleic acid monoester which is an intermediate product prepared from the fumaric acid monoester is greatly improved; on the basis, aluminum chloride is used as a catalyst of an isomerization reaction in the step S2 to catalyze isomerization of the intermediate product maleic acid monoester, and the fumaric acid monoester is synthesized by a chemical method. The preparation method is simple and convenient to implement; the preparation conditions are mild, and the method is environment-friendly; and the preparation cost is low, the yield is high, and no by-product is generated, so that a complicated purification process is not needed. 本发明属于生物化工技术领域，具体涉