By　employing　the　failure　curve　of　Hoek-Brown　criterion　as　a　failure　curve　in　the　meridian　plane,　as　well　as　the　triangle　failure　curve　of　a　unified　strength　criterion　as　a　failure　pattern　in　the　deviatoric　plane　of　a　rock,　a　new　three-dimensional　strength　criterion　is　proposed　for　an　intact　rock.　In　the　meridian　plane,　the　proposed　criterion　is　nonlinear　and　can　simulate　the　effect　of　hydrostatic　pressure　well;　In　the　deviatoric　plane,　the　failure　curves　change　from　the　MN　curved　triangle　to　the　DP　circle　and　can　take　account　of　the　influence　of　intermediate　principal　stress　properly.　The　failure　surface　of　the　new　strength　criterion　is　continuous,　smooth　and　convex.　It　can　be　thusly　employed　to　develop　a　yield　function　for　the　constitutive　model　of　rocks.　The　proposed　criterion　has　clear　physical　meanings　and　only　three　parameters　need　to　be　determined　by　experimental　results,　namely　σc,　mi　and　mt.　By　the　simple　determined　method　for　parameter　mt,　the　parameters　for　the　proposed　criterion　are　reduced　to　σc　and　mi,　which　are　same　as　that　of　original　Hoek-Brown　criterion.　The　proposed　strength　criterion　has　a　good　agreement　with　the　experimental　data.　Moreover,　by　introducing　the　the　Geological　Strength　Index　(GSI),　the　proposed　strength　criterion　also　can　be　employed　to　simulate　the　strength　of　rock　masses.　©　2018,　Engineering　Mechanics　Press.　All　right　reserved.