The invention discloses a device and a method for calibrating a field thermo-physical property tester. The device comprises a buried pipe loop and an external main loop; the buried pipe loop comprises a sand box, the sand box is filled with uniform fine sand, a drilling hole is horizontally formed in the center of the sand box, and a single U-shaped buried pipe is inserted in the drilling hole; the external main loop adopts a structure that an outlet of a circulating water pump is connected with an inlet of a water tank, and an outlet of the water tank is connected with an inlet of the single U-shaped buried pipe through a second three-way valve; an outlet of the single U-shaped buried pipe is connected with an inlet of the circulating water pump through a first three-way valve; a first temperature sensor and a flow meter are arranged between the outlet of the single U-shaped buried pipe and the first three-way valve; a second temperature sensor is arranged between the second three-way valve and the inlet of the single U-shaped buried pipe; the first temperature sensor, the flower meter and the second temperature sensor are all connected with a data acquisition device; the to-be-calibrated thermo-physical property tester is incorporated into the external main loop through the first three-way valve and the second three-way valve. The device and the method disclosed by the invention can accurately calibrate the tester.