Currently, the monitoring system of ornamental fish culturing water quality has the problems such as high cost, poor flexibility and wiring difficulty. In order to solve these problems, a monitoring system was provided based on wireless sensor network. Realtime monitoring of water quality parameter was realized. When the dissolved oxygen was low, it can increase the oxygen content in time and ensure that the water quality was stayed at the best condition. The data acquisition node of this system can collect information of water quality and send the processed data information to USB gateway node and the GPRS gateway node by using wireless communication. The USB gateway node sent the data to computer by USB interface and the GPRS gateway node uploaded the data to data server, so that users can check the water quality data by visiting remote server on mobile phones. The research language of nodes was C language, which can realize collecting, processing and wireless sending of water quality parameter data. VB 60 was applied to develop upper computer software while the mobile phone application was developed by Android system. In the test phase, the communication performance of node was good and the key factor to increase reliability of the system was to choose proper radiofrequency power according to communication distance. As the deviation of the sensor was negligible in the test, this system can meet the demand of monitoring of ornamental fish culturing water quality, which made it possible to provide reliable realtime monitoring of water quality parameter in large scales.