The invention provides an improved screw mainframe structure. The improved screw mainframe structure is used in a compressor so that the compressor has a simple and reasonable structure, convenient operation and maintenance, low noise, high efficiency and low energy consumption. The structure comprises a screw mainframe; an air filter is connected with an air inlet control valve which is also connected with an air inlet of the screw mainframe; an outlet of the screw mainframe is connected with an oil-gas separator; an oil channel outlet of the oil-gas separator is connected with a thermostaticvalve, an oil cooler, an oil filter, an inner oil pipeline and the screw mainframe in sequence; a gas passage outlet of the oil-gas separator is connected with the air filter, the air inlet control valve, the screw mainframe, the oil-gas separator, an oil filter core, a minimal pressure valve, an aftercooler and an air supply ball valve in sequence. The improved screw mainframe structure is characterized in that: the oil-gas separator, the air filter, the oil filter, a fine filter core, the air inlet control valve, the thermostatic valve, the minimal pressure valve, a safety valve and the screw mainframe are integrated into a whole.