The invention provides a synthesis method of a DLin-MC3-DMA intermediate, the DLin-MC3-DMA intermediate is (6Z, 9Z, 28Z, 31Z)-triheptane-6, 9, 28, 31-tetraen-19-alcohol, and the synthesis method comprises the following steps: S1, carrying out substitution reaction on (6Z, 9Z)-18-bromooctadecane-6, 9-diene and nitromethane to obtain (6Z, 9Z, 28Z, 31Z), step S2, carrying out hydrolysis reaction on (6Z, 9Z, 28Z, 31Z)-19-nitrotriheptane-6, 9, 28, 31-tetraene to obtain (6Z, 9Z, 28Z, 31Z)-triheptane 6, 9, 28, 31-tetraen-19-ketone, and S3, the (6Z, 9Z, 28Z, 31Z)-triheptane-6, 9, 28, 31-tetraen-19-oneand a reducing agent are subjected to a reduction reaction, (6Z, 9Z, 28Z, 31Z)-triheptan-6, 9, 28, 31-tetraen-19-alcohol is obtained, and the reducing agent comprises sodium borohydride, potassium borohydride, lithium aluminum hydride or a mixture of sodium borohydride, potassium borohydride and lithium aluminum hydride. The synthesis method disclosed by the invention has the characteristics of simple process conditions, simplicity and convenience in operation, short route, high repeatability, higher total yield and contribution to industrial production.