The power-saving aeration system works with inverter by controlling the wastewater aerator power system of livestock farm and monitoring dissolved oxygen value. The system includes aeration pump, inverter and dissolved oxygen monitor. The power can start smoothly with suitable rotation speed continuously, therefore the life cycle of bearing and pump can be extended. In addition, it can operate automatically with connecting to computer. It can save power of 20-25 ％ under aerating wastewater for 24 hours constantly.