The invention relates to a synthesis method of 1,4-butane sultone and belongs to the technical field of compound synthesis. The synthesis method takes tetrahydrofuran and acetylchloride as raw materials and comprises the following steps: A, preparation of butylchloroacetate: placing tetrahydrofuran and zinc powder in a container, cooling to 15 DEG C or lower, beginning to dropwise add acetylchloride, after dropwise adding, heating to 45 DEG C, holding the temperature for 8-10 hours, then heating to 60 DEG C, holding the temperature for 1-2 hour, performing pressure reduction to extract butylchloroacetate, and B, preparation of 1,4-butane sultone: allowing butylchloroacetate, sodium sulfite and water to give a heating reflux reaction for 14-16 hour, performing pressure reduction till a solid is separated out, cooling to 45 DEG C or lower, dropwise adding methanol hydrochloride solution, performing stirring for 1-2 hours, cooling to 4-6 DEG C, performing suction filtration, performing pressure reduction on filtrate to extract methanol, water and acetic acid, then heating to 130 DEG C, performing high vacuum pressure reduction cyclization for 0.5-1 hour, heating to 150 DEG C, and thenperforming high vacuum pressure reduction to extract 1,4-butane sultone. The synthesis method is simple; a reaction process is mild and stable; a prepared target product is high in yield and purity,and very low in water content and acid content.