The invention discloses an expansion machine refrigeration subcooling and nano particle jet flow minimal quantity lubrication supply system. The system comprise an expansion machine, a nano fluid minimal quantity lubrication supply system and an outer mixing nozzle, wherein the expansion machine is used for conducting isentropic expansion cooling on compressed air introduced into the expansion machine so as to form low-temperature cold air; the nano fluid minimal quantity lubrication supply system comprises a pump, a camshaft and a piston, and the camshaft is connected with an electromagnetic speed-adjustable motor; the electromagnetic speed-adjustable motor is used for driving the camshaft to rotate so as to drive the pump and the piston to move periodically and oppositely, and accordingly nano fluid is conveyed into an oil conveying pipe; the outer mixing nozzle comprises a nozzle gas inlet tube and a nozzle spraying needle, the oil conveying tube stretches into the nozzle gas inlet tube, a thermal insulation tube is arranged between the oil conveying tube and the nozzle gas inlet tube, and the low-temperature cold air is introduced into the thermal insulation tube and the nozzle gas inlet tube; one end of the nozzle spraying needle communicates with the oil conveying tube, and the other end of the nozzle spraying needle outwards extends out of the outer mixing nozzle; and the nano fluid in the oil conveying tube is sprayed out of the nozzle spraying needle and atomized after being blended with the low-temperature cold air sprayed out of the outer mixing nozzle.