The invention provides a method for producing a light-color polysulfide silane coupling agent by an aqueous phase process without a buffer agent. The method specifically comprises the following steps: (a) synthesis of a sodium polysulfide aqueous solution, namely adding sodium chloride, sodium hydroxide, sulfur and deionized water into a reactor, stirring and heating to 50-70 DEG C, reacting until the solid is completely dissolved, and preserving heat; (b) addition of a catalyst, namely adding a phase transfer catalyst aqueous solution into the sodium polysulfide aqueous solution, and mixing uniformly; (c) synthesis of a crude product, namely in a stirring state, adding (3-chloropropyl)triethoxy-silane into the solution, controlling the reaction temperature at 70-85 DEG C, and preserving heat; (d) phase separation, namely separating an organic phase on the upper layer from an aqueous phase on the lower layer in the solution, and removing solids in the organic phase; and (e) decoloration and purification, namely decoloring the treated organic phase solution and purifying by distillation to obtain the light-color polysulfide silane coupling agent. The polysulfide silane coupling agent prepared by the method has the advantages of safety and reliability in production, no polymerization, light color, few impurities, high content of active ingredients and high yield.