The invention relates to a method for hydrolyzing organochlorosilane, which is a process for continuously preparing polysiloxane by changing the solubility of hydrogen chloride in a pressure increasing and reducing mode. The method comprises the following steps of: hydrolyzing the organochlorosilane and water in a stoichiometric ratio, and low-concentration saturated circulating acid water under the pressure increasing condition to obtain high-concentration unsaturated acid water and the polysiloxane; adding the high-concentration unsaturated acid water and the polysiloxane, which are needed to be desorbed, in a hydrolysis system into a second-stage phase separator through a first-stage phase separator, and continuously circulating the residual high-concentration unsaturated acid water inthe hydrolysis system; separating on the top of the second-stage phase separator to obtain the polysiloxane, and adding the acid water at the bottom into a pressure reducing desorption kettle to obtain hydrogen chloride gas and low-concentration saturated acid water; and making the low-concentration saturated acid water return to the hydrolysis system for recycling. The organochlorosilane and thewater are continuously added into the system, the hydrogen chloride and the polysiloxane are obtained, a large amount of hydrogen chloride gas is recycled, oil-containing acid water is recycled, and the method has the characteristics that the method is energy-saving, economic and environment-friendly.