The　single　screw　compressor　(SSC)　is　widely　used　in　air　compression　and　refrigeration　systems　due　to　its　many　advantages.　The　meshing　clearance　between　the　screw　groove　and　gate　rotor　teeth　flank　has　a　significant　influence　on　the　compressor　performance.　In　this　paper,　mathematical　calculation　models　describing　the　internal　working　process　of　the　SSC　are　established　in　order　to　evaluate　the　thermal　dynamic　characteristics　of　the　compressor　under　varying　meshing　clearance　heights.　The　refrigerating　capacity,　volume　efficiency　and　adiabatic　efficiency　of　the　SSC　are　calculated　and　discussed.　Three　prototypes,　with　different　meshing　clearance　heights,　were　manufactured　to　study　the　internal　influence　mechanisms.　The　theoretical　model　was　verified　using　experimental　data　and　the　calculation　results　strongly　agreed　with　the　experimental　results.　Results　demonstrate　that　comparisons　of　volume　efficiency　and　adiabatic　efficiency　between　the　measured　and　calculated　results　exhibited　deviations　of　3.64%-7.98%　and　5.92%-9.4%,　respectively.　Based　on　the　models,　analysis　under　varying　meshing　clearance　heights　and　working　conditions　was　performed.　Taking　into　account　working　performance,　actual　manufacturing　conditions　and　manufacturing　cost　limitations,　a　meshing　clearance　height　range　from　0.01　mm　to　0.08　mm　is　suggested.　This　study　can　provide　important　theoretical　data　and　experimental　support　for　the　design,　manufacturing　and　optimization　of　single　screw　compressors.