The utility model provides a portable single screw compressor, belongs to compressor technical field. Constitute by a screw rod, two star gear meshings. Inside compressor housing was placed in, in tothe check valve, the gas outlet after compress with screw rod and star gear meshing linked to each other, prevents the interior gas reflux of high pressure chest, plays the effect of protecting compressor and drive compressors motor. The inside oil content device that sets up of compressor housing, gas -liquid two -phase thing that the device can come out to the check valve through the collision separation, plays the effect of oil gas crude separation. Seat (taking the temperature -sensing valve) by inhaling oil pipe, is strained through the oil of external connection to oil in the inside oilbath of compressor, through straining postinjection compressor inlet port, plays lubricated, sealed effect to the compressor.