Electro-hydraulic servo valve belongs to the high reliability, long life products. This paper chooses the method of accelerated degradation test to evaluate the life of electro-hydraulic servo valve. The method solves the problem of Long test period and high test cost of the Traditional life test . This paper does the research of electro-hydraulic servo valve accelerated degradation test based on wear mechanism. The purpose is to evaluate the electro-hydraulic servo valve’s performance using the shortest time . It puts the oil pollution as the stress test, the pressure gain as performance standard. And it does the SSADT for the electro-hydraulic servo valve, because there is no ready-made system for this test. It designs a test system for the pollution wear mechanism by itself. In terms of test data processing, this paper created accelerated Life Testing Model of Brown movement in drift and Inverse Power law model, in obtained the parameters estimation of model by using least square method and best linear unbiased estimation method, forecasted and analyzed normal lifetime and reliability of electro-hydraulic servo valve, verified the feasibility and efficiency of accelerated degradation testing.