Silicone resin is a highly crosslinked network-structured polyorganosiloxane, which has the dual characteristics of organic resins and inorganic materials. Generally, various mixtures of methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane or methylphenyldichlorosilane are used in the presence of an organic solvent such as toluene in Hydrolysis at lower temperature gives acidic hydrolysate. The initial product of the hydrolysis is a mixture of cyclic, linear, and crosslinked polymers, and usually also contains a considerable number of hydroxyl groups. The hydrolysate is washed with water to remove the acid, the neutral primary polycondensate is thermally oxidized in the air or is further polycondensed in the presence of a catalyst, and finally a highly cross-linked three-dimensional network structure is formed.