In aircraft system ground simulation test, thermal resistance and digital display instrument are widely used in the hydraulic, flight control and other experimental systems. Aiming at the problems of some thermal resistance and digital display instrument wiring complexity, inconvenient disassembly in each test system and the shortcomings of traditional measurement way, a field calibration system which is consist of field metrology well, portable thermometric instrument and temperature calibrator is presented. The field calibration system realizes thermal resistance and digital display instrument field whole calibration, also can calibrate thermal resistance and digital display instrument by segments. It avoids dismantling and reassembling, improves the work efficiency and has strong practicability.