The invention provides a synthetic method for methyl caulophine. The method comprises the following steps: with isovanillin and p-hydroxyanisole as raw materials, successively subjecting isovanillin to bromination and methylation so as to obtain 2-bromo-3,4- dimethoxy benzaldehyde; successively subjecting p-hydroxyanisole to acetylation, bromination, hydrolyzation, allyl etherification, Claisen rearrangement and methylation so as to obtain 1-allyl-4-bromo-2,5-dimethoxybenzene; successively subjecting the obtained 1-allyl-4-bromo-2,5-dimethoxybenzene and 2-bromo-3,4- dimethoxy benzaldehyde to Grignard reaction, ruthenium chloride/sodium periodate double-bond oxidation, reductive amination, pyridine chlorodichromate oxidation and intramolecular coupling so as to obtain 3-(2-(N,N-dimethylamino)methyl)-1,4,5,6-tetramethoxyl-9-H-fluorene-9-ketone, i.e. the method for synthesizing methyl caulophine is completed. The method in the invention has the advantages of mild reaction conditions, simple operation, easily-available raw materials and reagents, etc., and is suitable for large-scale production of pharmaceutical enterprises