The invention relates to a method for making hydrogen-containing silicone oil, in particular to a method for making methyl phenyl hydrogen-containing silicone oil for the encapsulation of LEDs. The method is characterized in that the methyl-phenyl cyclic siloxane (Dn<Me, Ph>), the tetramethyl tetraethyl cyclic tetra-siloxane (D4<Me, Et>) and hydrocyclotetrasiloxane (D4<H>) are taken as monomers; under the protection of N2, right amount of an end capping agent is added into the monomer mixture to be copolymerized under the action of a catalyst, after the polymerization, the catalyst is filtered and recycled, the low molecular compound of the obtained clear solution is removed in decompression and high temperature conditions, the clear solution without low molecular compound is cooled to the room temperature, and the target product is obtained. The method has the advantages of available raw materials, low cost, moderate conditions, simple technique, simple operation, environmental protection and convenient industrialization. The product made by the method can be widely applied to the enterprises which manufacture and use the LEDs, etc.