The　behavior　of　the　uncertain　disturbance　restraining　approaches　to　its　limitation　is　addressed.　Several　usual　systems　are　given　to　explain　that　many　H∞　control　problems　have　no　optimal　controllers.　The　asymptotic　performance　is　analyzed　in　the　case　of　H∞　state　feedback　controllers.　The　necessary　and　sufficient　conditions　are　given　for　the　existence　of　optimal　H∞　state　feedback　controller　in　Riccati　equations.　The　optimal　controller　makes　system　critical　stabilization　under　the　worst　case　disturbance.　The　optimal　feedback　controller　is　constructed.　A　simplified　existing　criterion　of　optimal　controller　is　given　by　two　Riccati　equations.