Abstract：The scale of pond farming in our country is increasing year by year, but we still fall behind the other developed countries in the modernization, scale and informatization. The real-time monitoring of the pond ecological environment will help to reduce unnecessary losses in fish farming. There are still many shortcomings in the pond observation system in our country, such as stability, reliability and extendibility of the system, continuous and real-time observation of the observation data, visualization of underwater environment, development and use of observation data, etc. Based on the above situation, this paper presented a novel solution of pond ecological environment online monitoring system, it built a new type of ecological environment online monitoring system by deploying multi-parameter sensor probes in pond circulating water inlet and underwater camera in selecting ponds, accessing to the data acquisition and control system, and then communicating with control center by GPRS/CDMA wireless transmission module or Internet to real-time update, show and release. The system realized the long-term, real-time, continuous, online monitoring of the ecological environment elements including temperature, salinity, depressure, chlorophyll, dissolved oxygen, and real-time live video monitoring of biological movement state and life habits. Besides, the system met the integration of nutrients elements such as ammonia nitrogen and nitrite. The data acquisition and control system was the core part of the on-line monitoring system of pond ecological environment, which was mainly responsible for the effective integration of multi parameter probe and camera through the introduction of the CAN bus distributed modular control technology. According to the system function module, it mainly included power supply module, master and slave control module, sensor module and wireless transmission module. The power supply module was responsible for the energy supply and distribution of the master-slave control module and the sensor module included +5 V, +12 V, +48 V by DC/DC module. The master-slave control module was responsible for management, control and communicate with the field CAN bus of each sensor module. The hardware part utilized the structure of core board plus bottom board where core board processor employed the ATMEL AT91SAM9263 and bottom board retained the necessary interface circuits, sensor module was responsible for CAN protocol conversion and power control including multi-parameter CAN module, camera CAN module, led CAN module and other extension CAN module. Wireless transmission module was responsible for communication with monitoring and control center by GPRS/CDMA DTU module. The control box inside was equipped with a card inserting mode similar to the PC computer mainboard, which comprised a power supply circuit board, a master-slave control circuit board, multi sensor circuit board, a bottom circuit board, etc. The bottom circuit board was provided with a multi-channel expansion slot, and the sensor module could be replaced according to the requirement. The control center was responsible for the release and show of observation data and live video including real time data monitoring platform and resource data sharing website. We have built the pond ecological environment online monitoring system to integrate WQM sensor, ROS C600 camera and LED light source device according to the actual needs of offshore area of Qingdao, Shandong and put into trial operation. It has proved the reliability and feasibility of the proposed solution and supplied reliable data support and technical guarantee for directing safety production and has broad application prospects.