The invention discloses a synthetic method of an anesthetic analgesic drug. According to the synthetic method, 4-piperidinecarboxylic acid is used as a raw material and subjected to alkylation, bromination, methylation, acylation and the like to prepare the anesthetic analgesic drug. The method avoids the usage of highly toxic cyanide, so the safety and controllability of operation are improved; the method avoids an elimination reaction in reaction process, thereby accelerating reaction speed and shortening reaction time; and the method reduces reaction temperature, shortens the reaction time,and is more suitable for industrial production.