Objectives   The electro-hydraulic servo valve operates in a harsh working environment but lacks integrated testability. In order to improve the usability and maintainability of electro-hydraulic servo valves, it is necessary to design a built-in test (BIT).

  Methods   A BIT method involving the characteristics of the valve amplifier is proposed. On this basis, the implementation of BIT software/hardware and the concrete design of anti-false alarm measures are given, and a closed-loop electro-hydraulic servo system is constructed for verification.

  Results   The verification test results show that this design method is feasible and can quickly detect faults online.

  Conclusions   The BIT method is an effective way to reduce the maintenance cost of the electro-hydraulic servo system life cycle, giving it certain engineering application value.