The invention discloses a parallel pipe pressure balance valve used for an internal combustion engine supply water tank and a method thereof. It includes supply water tank, left water chamber, spring, valve body, spool, right waterway, left waterway, right water chamber, radiator, sealing ring and back-stop column; The right end of the chamber is connected to the left end of the valve body, the right end of the valve body is connected to the left end of the right water chamber, the right end of the right water chamber is connected to the radiator, and there are two anti-retraction columns on the left side of the left water chamber and on the right side of the right water chamber. There is a valve core in the body, and the valve body and the valve core are tightly combined through a sealing ring. There is a spring in the left water chamber, and the two ends of the spring are respectively connected with the left side of the left water chamber and the left end of the valve core. Turn left onto the waterway. The present invention can carry out real-time and precise control on the amount of cooling liquid in the water channel of the radiator when there is a pressure difference between the supply water tank and the cooling pipeline, especially can prevent the instability of the flow change between the two caused by the up and down bumps of the vehicle, and improve the efficiency of the cooling system. stability and efficiency.