Electrohydraulic controller combines the electronic technology, hydraulic technology and the computer control technology, which is important in the promotion and development of the electrohydraulic control technology, in the expansion of application field of hydraulic technology has important significance. On the basis of further studying the existing design and development experience of electromechanical system control products both at home and abroad, and the latest development of the electrohydraulic controller is taken for reference, it introduces the electrohydraulic controller design based on STM32 microcontroller. Combining 32bit MCU and CPLD device, form the hardware and software parts of this electrohydraulic controller. With multiworking mode, this electrohydraulic controller can not only drive electrohydraulic equipment but control solvents infusion pump and supercritical analytical instruments. Through the controller to realize the high speed and high precision position control, reciprocating motion control and accurate pressure regulation control. And experiments have been done through the automatic back pressure regulator device of supercritical analytical system, it gets a satisfying control precision and control effect.