In the paper, the mapping relation between static characteristics of electro-hydraulic servo valve and fault pattern is analyzed. The method of multi-parameter fault pattern recognition of electro-hydraulic servo valve based on BP neural networks is introduced, which is researched based on tests. The result shows that the accuracy rate of fault pattern recognition is higher by adopting this method. Furthermore it can be combined with the test function of servo valve test stand to form a kind of testing system with self-study, automatic test and intelligence diagnosis.