Refrigeration　rotary　compressors　are　widely　used　in　air-conditioners.　A　rotary　compressor　has　a　special　rotor-bearing　system,　since　the　elastic　cantilevered　crankshaft　is　under　dynamic　transverse　forces　on　different　planes.　The　large　deformation　of　the　crankshaft　would　affect　the　thickness　of　the　oil　film,　wear　the　bearings　down　or　even　induce　the　rotor-to-stator　rubs.　It　is　considered　as　a　non-linear　fluid　structure　interaction　problem.　To　ensure　the　compressor　operating　well,　the　dynamic　behaviors　of　both　single-cylinder　and　twin-cylinder　compressors＇　crankshafts　at　various　speeds　are　analyzed.　The　influence　of　configuration　of　balancers　on　the　reliability　of　rotor　system　is　investigated　for　the　further.　Calculation　results　suggest　that　the　vulnerable　sections　of　crankshaft　vary　with　the　rotational　speed.　It　is　also　found　that　80%　of　the　dynamic　balance　is　the　optimum　design　condition　to　reduce　the　transverse　forces　on　crankshaft　and　the　wear-out　of　journal　bearings.　(C)　2014　Elsevier　Ltd　and　IIR.　All　rights　reserved.