Nonlinear　stochastic　static　analysis　is　carried　out　for　the　deflection　of　main　span　girder　of　a　self-anchored　suspension　bridge　by　response　surface　method　(RSM).　The　law　of　main　span　girder＇s　deflection　is　researched　with　the　variation　of　structural　parameters　such　as　material　properties,　geometric　dimensions　and　external　loads,　ect.　The　response　surface　function　does　not　contain　the　quadratic　cross　items.　In　the　finite　element(FE)　model　nonlinear　mechanics　behaviors　of　the　structure　are　considered　including　main　cable＇s　geometric　nonlinear　and　P-A　effect　of　tower　as　well　as　girder.　The　results　obtained　from　RSM　and　FEM　proved　that　the　RSM　is　applicable　to　predict　the　structural　nonlinear　response　for　self-anchored　suspension　bridges.　It　is　concluded　that　the　variation　of　the　area　and　modulus　of　the　main　cable　and　area　of　the　girder　have　significant　effect　on　the　deflection　of　girder,　and　the　various　weight　of　vehicle　axles　has　different　effect　on　it.