The invention discloses a method for preparing walnut oil by performing emulsion breaking on a walnut oil body by a water method, and belongs to the technical field of processing of plant oil and proteins. The walnut oil and walnut proteins are prepared by preparing walnut pulp, the walnut oil body, walnut oil I, walnut protein I, the walnut oil body in a heavy phase and walnut protein II, and combining the prepared materials. According to the method, no thermal treatment is carried out in the process of preparing the walnut pulp (or an extract of a walnut water phase), so that the walnut proteins and other components cannot be affected by thermal treatment; a light phase (the walnut oil body) part obtained by centrifugation can be subjected to efficient emulsion breaking by using the method, so as to obtain clear and fragrant walnut oil; by condition optimization, 98 percent or above of oil, obtained by centrifugation, in the walnut oil body can be released. The method is simple in process, and a centrifugation machine is used as main equipment; no enzyme preparation or organic solvent is used, so that the preparation process is environment-friendly and efficient.