Abstract: Aim\ The integration of the fuzzy produced rules based fault diagnosis expert system and neural networks, and conversion from the rules based reasoning networks to neural networks were discussed Methods In the converting process, the certainty factors of the conditions and the rules were respectively merged in the inputting and the outputt ing information of the learning samples of the neural network The details of the actual example were described Results Conversion from the rules based reasoning networks to neural networks was accomplished The fuzzy quick reasoning diagnosis and the automatic knowledge acquisition based on neural networks were realized Conclusion By the test of the actual example, it is shown that the method is effective and reliable, and solves the conflict in the fuzzy rules based reasoning Neural networks are combined with fuzzy rules based expert system effectively