The invention relates to a brake fluid cooling device. The brake fluid cooling device comprises a hydraulic oil tank and a brake system, wherein the brake system comprises a brake, a shunt valve which is arranged at the front end of the brake, and an oil return valve block which is arranged at the rear end of the brake; a gear pump, a filter and a flow control valve are arranged on an oil inlet pipeline between the shunt valve and the hydraulic oil tank in sequence; a cooler and a bypass valve are arranged on an oil return pipeline between the oil return valve block and the hydraulic oil tank in sequence; the bypass valve is provided with an oil discharge passage, an oil return passage, an overflow passage and an oil return header pipe which is connected with the hydraulic oil tank; and the oil return passage is connected with the cooler. According to the brake fluid cooling device, hydraulic oil at lower temperature in the hydraulic oil tank replaces brake fluid at high temperature in the brake, and the brake fluid is cooled to achieve an effect of reducing the temperature of a brake block; and meanwhile, through overflowing of overflow branches and oil discharge of an oil discharge pipeline, the service life of the brake is prolonged, the reliability of the brake is increased, and a certain cooling effect on the hydraulic oil of the hydraulic oil tank is achieved.