Abstract: The invention relates to a preparation method of vinyl-terminated siloxane. R2R3Si(OR4)2, R12(CH2?CH)SiOSi(CH?CH2)R12, an organic acid and a catalyst are added into a reaction bottle according to the molar ratio of 1:1-1.5:1-2.5:0.005-0.01, wherein R1 is alkyl, R2 and R3 are alkyl, aryl or substituted alkyl, substituted aryl identically and differently, and R4 is alkyl, heating is performed to 50-80° C. while stirring, the stirring reaction is performed at the temperature for 5-30 min, then a dehydrating agent is added, and the reaction is continuously performed for 2-5 h at the temperature of 50-80° C.; and the temperature is reduced to room temperature after the end of reaction, and then dilution, washing with water to neutral, collection of an organic phase, drying, filtering, concentration, reduced pressure distillation and collection of a fraction at corresponding pressure and temperature are sequentially performed so as to obtain a vinyl-terminated siloxane compound product.