The invention belongs to a synthesis method of bupivacaine. The method comprises: adding 2 piperidinecarboxylicacid into aqueous alkali, dropwise adding Cbz and alkaline water, after finishing dropwise adding at normal temperature, reacting for 12 hours, after reaction, extracting with diethyl ether, washing a water layer to be weak-acid with 18% of diluted hydrochloric acid, extracting with the diethyl ether again, combining an diethyl ether layer, drying and filtering, and concentrating to obtain a dried product; adding the dried product into a DMF solvent, then adding a catalyst for reaction for 1 hour at normal temperature, then adding 2,6-dimethylaniline, reacting for 18hours at normal temperature, adding water and ethyl acetate for washing, taking an organic layer, drying and filtering, and concentrating to obtain a dried concentrated product; adding the dried concentrated product into a solvent, then adding a catalyst, pressurizing and introducing hydrogen, filtering after reaction and concentrating to obtain a dried product; adding the product in the above step into a solvent, dropwise adding bromo-n-butane at normal temperature, after dropwise adding, rising temperature to 80 DEG C for reacting for 12 hours, adding diluted hydrochloric acid, slowing cooling to normal temperature, and crystallizing, filtering and drying to obtain the product. The synthesis method has the advantages of higher yield, smaller pollution and low equipment requirement.