By taking an equipment hydraulic leg circuit as a research object, common fault mechanisms of circuits are analyzed, and fault characteristic parameters are extracted. Based on the Unscented Kalman Filter (UKF), Forecasting methods of the bi-directional hydraulic lock performance deterioration were built. Work index indicators were constructed. The abnormal threshold of the work index was determined. The working life of the bi-directional hydraulic lock was estimated. Based on MATLAB/Simulink, the simulation model of the bi-directional hydraulic lock was set up. The equipment related operation parameters were set. The performance with pressure and temperature variation tendency of the bi-directional hydraulic lock is simulated in its life circle. The research result provides scientific guidance to the component maintenance support scheme.