Press wet multiple disk brake is widely used in automobile, machine tools, plane, construction machinery, mining machinery and other large equipments. Press wet brake action is mainly controlled by matched hydraulic system, so whether the selection and design of hydraulic system are reasonable has direct impact on job performance of press wet brake. Taking the press wet brake of a mined rubbertired cart as an example, starting from the working principle of the brake hydraulic system, the design and type selection of the hydraulic system were analyzed and discussed.