The invention relates to the field of adhesives, in particular to low-viscosity 107 silicone rubber and a preparation method thereof, and aims at providing the low-viscosity 107 silicone rubber preparation method which is simple in reaction process control and stable in product viscosity. The method specifically comprises the steps of 1 dewatering, wherein in a non-vacuum state, decompression dewatering are performed on dimethyl siloxane mixed ring bodies at the temperature of 80 DEG C-100 DEG C for 0.5-1.5 hours; 2 catalyzing, wherein a basic catalyst is added when the temperature is increased to 100 DEG C-115 DEG C, the temperature is increased continuously, the reaction temperature is controlled at 130 DEG C-160 DEG C, and the balanced reaction time is controlled for 0.5-1.5 hours; 3 degrading, wherein degrading is performed by adding water; 4 neutralizing, wherein a neutralization reaction is performed by adding a neutralizing agent; 5 fraction collecting, wherein vacuum is started after the neutralization reaction, the materials are heated to reach the temperature of 120 DEG C-195 DEG C, the vacuum degree is controlled and kept at negative 0.08 MPa-negative 0.098 MPa, and fractions are collected until no fraction is dropped. The preparation method is high in yield, and the obtained low-viscosity 107 silicone rubber can be widely applied to electronic industry and aviation and military industry.