Water-lubricated　single　screw　air　compressor　is　lubricated　and　sealed　by　injecting　water　into　the　working　chamber.　A　mathematical　model　of　the　working　process　of　a　water-lubricated　single-screw　air　compressor　was　established　in　this　study.　The　influences　of　the　diameter　of　the　water　injection　aperture　and　rotation　speed　on　compressor　performance　was　analyzed　through　the　model.　Weber　number　was　introduced　to　evaluate　and　analyze　the　atomization　effect.　Results　show　that　the　discharge　temperature　is　effectively　reduced　by　increasing　the　diameter　of　the　water　injection　aperture,　resulting　in　the　compression　process　of　the　compressor　moving　towards　an　isothermal　state.　Under　rated　conditions,　the　increase　in　the　diameter　of　the　water　injection　aperture　from　5　mm　to　7　mm　reduced　the　discharge　temperature　of　the　compressor,　improved　the　volume　efficiency,　and　the　adiabatic　efficiency　by　40.4　K,　3.99%,　and　7.57%,　respectively.　Although　the　increase　in　rotation　improved　the　efficiency　of　the　compressor,　there　was　a　decrease　in　the　cooling　and　sealing　effect　due　to　a　reduction　in　the　water-air　ratio.　Therefore,　the　impact　of　an　increase　in　speed　on　the　efficiency　of　the　compressor　was　gradually　weakened.　With　the　increase　of　the　diameter　of　the　water　injection　aperture,　the　average　diameter　of　atomized　droplet　increased.　The　minimum　water　flow　rate　corresponding　to　different　water　injection　apertures　was　determined　according　to　Weber　number.　©　2022,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.