The invention relates to a method for synthesizing N-acetylmorpholine. The method comprises the following steps of adding N-acetylmorpholine, an acetic acid entrainer, a dehydrating agent and water into a tower bottom, heating until a residue is boiled, raising vapor, condensing, layering condensate into an oil phase and an aqueous phase, accumulating the aqueous phase in a layering device, refluxing the oil phase from an upper material inlet of a rectifying section, when the tower top temperature reaches 84.6 DEG C, adding morpholine from the upper material inlet of a reaction section, adding acetic acid from the lower material inlet of the reaction section, adding the acetic acid entrainer from the upper material inlet of a dehydrating section, reacting morpholine and acetic acid to produce morpholine salt, dehydrating morpholine salt to produce N-acetyl morpholine and water, azeotroping water and the dehydrating agent, passing through the dehydration section, the reaction section and rectifying section to enter the condenser for condensing, layering the condensate into the oil phase and an aqueous phase, extracting the aqueous phase, refluxing the oil phase and extracting N-acetylmorpholine from the tower bottom. The method for synthesizing N-acetylmorpholine is high in production efficiency, low in energy consumption, small in device investment, short in process and free of pollution and the large-scale continuous production can be achieved.