Abstract: Through the study of intelligent diagnostic technology, artificial intelligence multi-agent technology is used in aircraft hydraulic system integrated monitoring and control system. A multi-agent collaborative diagnosis expert system is built based on multi-oil analysis, and the aircraft hydraulic system condition monitoring expert system (AHMES1.0) is developed and applied to the wear fault monitoring of aircraft hydraulic system. The expert system is composed of contamination analysis agent, physicochemical analysis agent, ferrograph analysis agent, spectrometric analysis agent, fusion diagnosis agent and integrated diagnostic agent. Integrated diagnostic agent is responsible for the control and management of other agents for the cooperation diagnosis. What’s more, according to the actual situation of aircraft hydraulic system diagnosis, each agent diagnosis rule is given. Finally, the test results of the actual fault case show the effectiveness of the multi-agent diagnosis.