The invention discloses a field calibration device for an extra-large flow air sampler for radiation environment monitoring. The field calibration device comprises a detection end, a communication unit and a display operation end, wherein the detection end comprises a Roots flow sensor, a temperature sensor, a pressure sensor and a signal collecting unit; the communication unit is arranged between the detection end and the display operation end; the display operation end comprises a signal processing and controlling unit, a display screen, a touch screen and a memory; the Roots flow sensor, the temperature sensor and the pressure sensor are used for detecting volume flow, temperature and pressure of gas in a gas output port of the sampler respectively and inputting three kinds of signals to the signal collecting unit; the signal collecting unit is used for amplifying the received three kinds of signals and transmitting the signals to the signal processing and controlling unit through the communication unit; the signal processing and controlling unit is used for compensating the received amplified signals and displaying the signals on the display screen. With adoption of the device, real-time calibration and moving calibration can be realized, the calibration precision reaches 2%, and large-flow and high-precision gas measurement functions are realized.