The invention discloses a method for synthesizing sec-butyl-disulfide under phase transfer catalysis by a non-solvent method, and belongs to the technical field of fine chemicals synthesis. In the method, cheap and easily obtained industrial sodium sulfide and sulfur are used as raw materials to prepare sodium disulfide water solution, and the sec-butyl-disulfide is synthesized through the reaction of sodium disulfide and sec-butyl bromide by adopting phase transfer catalysis technology without organic solvent and using quaternary ammonium salt as a phase transfer catalyst. The method has the advantages of mild reaction conditions, simple and convenient operation, high atom utilization ratio and little environment pollution; the content of the sec-butyl-disulfide in a crude product mixture is more than 96 percent; and the yield is more than 92 percent. The water phase after reaction is condensed and crystallized to recover sodium bromide which can reach industrial grade, so as to lower production cost.