Control valve is the most widely used intelligent mechanism in industry today. In the field of industrial automation process control, the control valve receives the control signal from the control unit and uses the power operation to change the final control element of the process parameters such as the medium flow rate, pressure, temperature and liquid level. The regulating valve is generally composed of actuator and valve. According to the stroke characteristics, the regulating valve can be divided into straight stroke and angular stroke; According to the power used by the actuator and its functions and characteristics, it is divided into linear characteristics, equal percentage characteristics and parabolic characteristics. The regulating valve is suitable for air, water, steam, various corrosive media, mud, oil and other media. The regulating valve and accessories include: pneumatic regulating valve, electric regulating valve, self operated regulating valve, manual regulating valve, pneumatic diaphragm actuator, electric actuator, electric valve positioner, electric valve regulating module, etc. According to its energy form, the regulating valve can be divided into three categories: pneumatic, electric and hydraulic. Pneumatic and electric are commonly used in the production process. The development direction of regulating valve is mainly intellectualization, standardization, miniaturization, rotation and safety.