The invention relates to a synthetic method of a SMND-309 compound shown in a formula 6. The method comprises the following steps of: reacting a compound 1 shown in a formula 1 with carbon tetrabromide and triphenylphosphine to obtain a compound 2 shown in a formula 2, then reacting the compound 2 with benzyl bromide in the presence of potassium carbonate so as to enable phenolic hydroxy groups to form benzyl ether, obtaining a compound 3 shown in a formula 3 under the action of tetrahydropyrrole, leading in methyl acrylate groups through Heck reaction under the action of palladium acetate, triphenylphosphine, triethylamine and potassium carbonate, obtaining a compound 4 shown in a formula 4 through hydrochloric acid hydrolysis, carrying out Perkins condensation reaction of the compound 4 and heliotropin under the action of toluenesulfonic acid, esterfying with methyl alcohol to obtain a compound 5 shown in a formula 5, and carrying out deprotection under the action of boron tribromide to obtain the target compound SMND-309 shown in the formula 6. The SMND-309 compound synthetic method has the beneficial effects that reaction steps are few, the yield is high, the operation is convenient, reaction conditions are mild, the product configuration is single, and the foundation is laid for the further application of the SMND-309 compound.