In　micro-nano-scale,　the　gas-film　thickness　of　aerodynamic　gas-lubricated　bearings　is　close　to　the　mean　free-path　of　gaseous　molecules.　The　gas　rarefied　effect　is　a　key　influence　factor　to　the　dynamic　performance　of　self-acting　gas　bearings.　In　this　paper,　the　dynamic　gas　film　pressure　and　film　thickness　are　expressed　as　the　complex　form　with　periodic　disturbance　of　the　journal.　The　dynamic　Reynolds　equation　for　the　ultra-thin　film　lubrication　is　solved　in　virtue　of　the　toolbox　of　partial　derivative　equation　(PDE)　of　MATLAB.　Then　the　dynamic　stiffness　and　dynamic　damping　coefficients　of　hydrodynamic　gas　bearings　can　be　obtained.　The　effects　of　different　radius　clearance,　the　modified　models　of　gas　rarefied　effect　and　different　bearing　parameters　on　the　dynamic　characteristic　coefficients　of　gas　bearings　are　analyzed.　The　results　show　that　the　dynamic　stiffness　coefficient　of　aerodynamic　journal　bearings　is　significantly　reduced　and　the　dynamic　damping　coefficient　is　increased　as　the　increase　of　gas　rarefied　effect　and　decrease　of　radius　clearance.　Moreover,　the　parameter　of　the　aerodynamic　pressured　bearing　has　a　little　influence　on　the　dynamic　characteristics　when　the　radium　of　clearances　is　reduced　to　nanometer　scale.　©　2019,　Nanjing　Univ.　of　Aeronautics　an　Astronautics.　All　right　reserved.