The　ring　speed　ratio　largely　determines　the　steady　state　and　dynamic　response　of　a　floating　ring　bearing　(FRB).　Extensive　experiments　demonstrate　FRB　speed　ratios　have　a　strong　nonlinear　relationship　with　journal　rotative　speed,　but　theoretical　predictions　show　significant　discrepancies　with　test　data.　Aiming　at　solving　this　problem,　a　thermal-hydrodynamic　model　is　established　to　investigate　the　lubrication　performance　of　FRB.　The　state　and　dynamic　performance　of　FRB　under　several　typical　operational　conditions　are　calculated.　The　relationship　between　speed　ratio　and　journal　rotative　speed　is　investigated　under　isothermal,　conducive　and　adiabatic　conditions.　The　influence　of　ring　material　on　the　speed　ratio　is　also　addressed.　Furthermore,　the　fitness　conditions　of　the　classical　analytical　formula　of　speed　ratio　is　discussed.　The　main　conclusions　are　as　follows:　the　isothermal　model　overestimate　the　speed　ratio　significantly　under　a　wide　range　of　rotative　speed,　whereas　the　results　of　conducive　thermal　model　shows　a　good　agreement　with　existing　experiment　data.　Both　the　theoretical　and　experimental　results　show　that　the　speed　ratio　increase　sharply　at　low　speed,　then　decrease　gradually　with　further　increasing　journal　rotative　speed.　The　ring　speed　ratios　decrease　under　moderate　and　high　shaft　speed　is　mainly　due　to　the　difference　of　the　lubricant　viscosity　between　inner　and　outer　film　and　the　variation　in　film　clearances　owing　to　thermal　growth　of　the　components.　Hence,　the　thermal　effect　is　mandatory　for　reliable　FRB　design.　©　2017　Journal　of　Mechanical　Engineering.