Electrodeionization (EDI) is a popular method of water treatment in the current field of water treatment. EDI module mainly absorbs the charged ions in water through the cation exchange resin and realizes the ion removal of water by applying an electric field to make the charged ions move in a directional way and pass through the cation exchange membrane with selective permeability. The existing EDI module has a low integration degree and the working current cannot be adjusted intelligently according to the field environment. In order to solve the problem of low integration degree, this paper designs an EDI module that integrates the EDI module, sensor, controllable constant current source module, and main controller. Meanwhile, in order to solve the problem that the current EDI working current cannot be adjusted in real-time with the environmental water quality, an EDI module output current control method based on fuzzy PID and a main controller hardware circuit based on the adjustable constant current source circuit of a microcontroller digital-to-analog converter (DAC) are designed to adjust the output current of EDI module intelligently. Then the control model of the control system is established by Matlab respectively using the PID control method and fuzzy PID control method, and the simulation is compared. In this paper, the hardware and software of the module are developed based on STM32. The experimental results show that the designed EDI module can realize accurate and fast control of water quality.