With the increase of network's complexity, the influence of network failure is more and more critical. Fault diagnosis performance should be improved too, especially on the automation and intelligence. According to the experts' experience to diagnose network fault, this paper designs a production rule for it. Afterwards, paper implements network fault diagnosis by rule reasoning, and generates repair scheme automatically. Furthermore, the system can share the fault knowledge among all the agents, so that the whole network can be immune from the new fault automatically. Finally, we design and realize a set of intelligent network fault diagnosis & repair system, which can finish network fault diagnosis & repair work automatically.