The　expansion　natural　gas　liquefaction　process　combining　two-stage　compression　and　two-stage　expansion　is　generally　utilized　for　the　portable　liquefied　natural　gas　system.　Two-stage　compression　includes　a　low-pressure　compressor　and　a　high-pressure　compressor.　Thus,　the　compressors＇　performance　directly　affects　the　natural　gas　liquefaction　process.　A　high-pressure　single　screw　compressor　was　designed　and　manufactured　in　this　study　to　obtain　the　performance　of　the　high-pressure　compressor.　Its　performance　test　system　was　built　under　the　rotation　frequency　from　35　Hz　to　50　Hz　and　at　the　exhaust　pressure　from　1.5　to　3.5　MPa.　The　experimental　results　show　that,　when　the　compressor　works　at　a　rotation　frequency　of　50　Hz　and　an　exhaust　pressure　of　3.5　MPa,　its　actual　flow　rate,　shaft　power,　specific　power　and　volumetric　efficiency　are　0.752　Nm(3)/min,　20.48　kW,　27.23　kW/　(m(3)center　dot　min)　and　0.52,　respectively.　The　experimental　results　show　that　the　compressor＇s　performance　meets　the　design　requirements,　which　can　be　used　for　natural　gas　liquefaction.