Abstract: According to the conditions of poor control equipment and low reliability in China’s aquaculture, the paper presented a distributed control system with high cost-effective. The each functional unit has a microcontroller. Each module was designed with different hardware to achieve the corresponding functions and RS-485 bus module was used for communication. The system can display in real-time with LCD for various water quality parameters and let operator real data easily. The experiment show that the distributed control system(DCS) is reliable and obviously to reduce the fluctuation of dissolved oxygen. The dissolved oxygen content of pond can be inereased by 1mg/L with the DCS.