In　this　paper,　the　experiments　were　performed　on　the　triaxial　strength　and　deformation　behavior　for　plain　high-strength　concrete　(HSC)　at　different　kinds　of　stress　ratios　(alpha　=　sigma(1)　:sigma　(2)　:sigma　(3)　=　0.00:　0.00:-1,　0.10:　0.10:　1;　0.10:　0.27:　1;-0.10:-0.42:-1;　0.10:-0.52:-1;　0.10:-0.77:-1;　0.10:　1:　1),　after　the　exposure　to　normal　and　high　temperatures　of　20,　200,　300,　400,　500　and　600　degrees　C,　using　a　large　static-dynamic　true　triaxial　machine.　The　triaxial　compressive　strengths,　peak　strain　and　stress-strain　curves　were　measured.　The　effects　of　the　temperatures　and　stress　ratios　on　the　failure　modes,　strength　and　deformation　of　HSC　were　studied　and　analyzed,　and　the　corresponding　conclusions　were　given.　The　experimental　results　showed　that　the　ratio　of　the　triaxial　to　its　uniaxial　compressive　strength　depends　on　the　stress　ratios　and　temperature　levels.　An　orthotropic　constitutive　model　with　temperature　parameters　for　plain　HSC　under　triaxial　compression　is　established,　which　is　in　good　agreement　with　the　experimental　results