The invention relates to the technical field of chemical engineering, in particular to a preparation method for low hydrogen-containing silicon oil. The preparation method adopts high hydrogen-containing silicon oil (202) and dimethylcyclosiloxane (DMC) as raw materials and hexamethyldisiloxane (MM) as an end-capping agent, under the catalysis of a solid superacid, the temperature is increased to 50-140 DEG C for a telomerization, and the low hydrogen-containing silicon oil is prepared. Compared with the prior art for preparing the low hydrogen-containing silicon oil under the catalysis of vitriol, the preparation method adopts the solid superacid as a catalyst, the catalyst has a good catalysis effect and can be reused, neutralization and washing are not required during the preparation method, and short time is taken by the whole preparation process, continuous method industrial production is likely to be achieved, and the production efficiency is high.