The electro-hydraulic servo valve is an automatic control valve. It is both an electro-hydraulic conversion component and a power amplification component. Its function is to convert a small-power analog signal input to a large response with the size and polarity of the electrical signal and a fast response. Power hydraulic energy flow and pressure output, so as to control the displacement, speed, acceleration, and force of the hydraulic actuator. The electro-hydraulic servo valve is usually composed of an electrical-mechanical converter, a hydraulic amplifier, and a detection feedback mechanism.