A process of synthesizing praziquantel is provided. According to the process, beta-phenylethylamine and dichloromethane are added into a reactor and subjected to an acylation reaction; the mixture is stirred and cooled and the acylation reaction temperature is lowered to 0-35 DEG C or below; chloroacetyl chloride and liquid caustic soda are added dropwise under temperature control of the reaction solution; the pH value of the acylation reaction solution is controlled to be 6-12 during a dropwise adding procedure; and after the dropwise adding procedure is finished, the temperature is maintained, and the mixture is stirred and layered. A one-pot method is adopted by the process, the cost of the process is low, operation methods are simple and controllable, environment protection safety is good and product quality is stable.