Gamma Ray Integrated Detectors aim to monitor and locate gamma-ray bursts. However, environmental factors can affect the detectors’ output signal, necessitating an on-orbit calibration to ensure accuracy. This paper proposes a new method for on-orbit calibration of scintillator detectors, utilizing a combination of a pure Sn sheet and a 241Am exemption source. Since the GAGG scintillator equipped on the GRID-06 detector has a Gd absorption edge (50.2 keV), two calibration energy points of 59.5 keV and 25.3 keV were constructed to calibrate the upper and lower energy bands of the Gd edge respectively, while the 241Am source was shielded with a Sn sheet. Experimental data revealed that the count rate of the 59.5 keV full-energy peak of the 241Am source decreased from 296 cps to 78 cps after being shielded with a 0.15 mm Sn sheet, while the count rate of the 25.3 keV characteristic X-rays produced by the excitation reached 30 cps. Based on these results, the proposed calibration method was analyzed and found to be applicable for observing GRBs, with the lower limit of flow intensity within 0∼100 keV of 95.5% of the gamma bursts being calculated.