The invention relates to a preparation method of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and belongs to the technical field of battery electrolyte additives. The preparation method takes trimethyl-vinyl chlorosilane as a raw material, and ammonia is introduced into trimethyl-vinyl chlorosilane for reaction. The preparation method comprises the following steps: A, controlling pressure to 2-5 kg NH3 pressure, performing the reaction at 80-150 DEG C for 1-6 hours, and after the reaction ends, adding a dichloroethane digestion product, and B, adding the product into a polymerization inhibitor, and performing molecular distillation under the condition of a temperature of 35-85 DEG C and a vacuum degree of 1-5 Pa to obtain colorless and clear liquid. The preparation method is simple; through combination of temperature control and post-treatment operation, and prepared 1,3-divinyl-1,1,3,3-tetramethyldisilazane is high in yield and purity and more suitable for the battery electrolyte additives.