According to requirement of stability on working status for the automatic fertigation system, the monitoring devices and monitoring methods of water supply status, fertilizer suction status, nutrient mix status and irrigation/fertilization status were designed. Intelligent controller controlled automatic fertigation systems based on the monitoring results of working status of all aspects. At last the prototype was trial-manufactured. The performance of the prototype was tested. The test results showed that the working status of automatic fertigation system was stable, and the system could satisfy the requirements of irrigation and fertilizer proportion in greenhouse. The problem of monitoring working status of automatic fertigation system was solved.