A　fuzzy　robust　nonlinear　programming　model　is　developed　for　the　assessment　of　filter　allocation　and　replacement　strategies　in　hydraulic　systems　under　uncertainty.　It　integrates　the　methods　of　fuzzy　mathematic　programming　(FMP)　and　robust　programming　(RP)　within　the　mixed　integer　nonlinear　programming　framework,　and　can　facilitate　dynamic　analysis　and　optimization　of　filters　allocation　and　replacement　planning　where　the　uncertainties　are　expressed　as　fuzzy　membership　functions.　In　modeling　formulation,　theory　of　contamination　wear　of　typical　hydraulic　components　is　introduced　to　strengthen　the　presentation　of　relationship　between　system　contamination　and　work　performance.　The　fuzzy　decision　space　is　delimited　into　a　more　robust　one　by　specifying　the　uncertainties　through　dimensional　enlargement　of　the　original　fuzzy　constraints.　The　piecewise　linearization　approach　is　employed　to　handle　the　nonlinearities　of　problem.　The　developed　method　has　been　applied　to　a　case　of　planning　filter　allocation　and　replacement　strategies　under　uncertainty　and　the　generated　optimal　solution　will　help　to　reduce　the　total　system　cost　and　failure-risk　level　of　the　FPS.