This paper attempts to survey the compositions, functions and operation of an automatic control system for irrigation. By means of the application of technologies such as computer technology, telecommunication technology, autocontrol technology and modern agriculture technology, the automatic control system for irrigation can be realized. The system provides real-time monitoring for relevant parameters via sensors installed in field. All signals are delivered directly to a central controller through radio network. Based on the start and stop of pump unit and open and close of solenoid valve, the master computer can realize automatic irrigation and therefore provide a new water-saving equipment for the irrigation.