Response　surface　methodology　(RSM)　is　used　to　express　stress　and　displacement　constraints　in　the　linear　form　with　respect　to　design　variables.　The　objective　function　of　minimizing　the　weight　of　truss　structure　is　transformed　into　a　second-order　form.　The　original　model　is　formulated　as　a　standard　QP　model.　Sensitivity　analyses　by　RSM　and　Mohr　integration　are　compared.　An　example　is　presented　to　illustrate　the　effectiveness　and　efficiency　of　RSM　in　application　to　truss　optimization.