Equipped with multi-spring actuator, the pneumatic diaphragm control valve directly connected with single seat has the advantages of compact structure, light weight, sensitive actions, S streamlined fluid channel, small loss of pressure drop, large valve capacity, accurate flow characteristic and convenient disassembly and assembly. It is widely used for precise control of media, such as gas and liquid, the process parameters, such as pressure, flow, temperature and liquid level, shall be maintained at the given value. It is especially suitable for the workplace where the small leakage and balance pressure between front and back of valve can be allowed.