The reliability of Ni-Cr alloy thin film resistors were tested by an aging test under an environment of 85 ℃ and 85% relative humidity for 3 000 h. The results show that the thin-film resistors exhibit two failure modes, resistance drift, and open circuit, after aging tests at 85 ℃ and 85% relative humidity. The failure mechanism of both failure modes was further analyzed, and the causes of failure were clarified. The failed resistors were examined by a 3D laser scanning microscope, scanning electron microscope, energy dispersive spectroscopy, and focused ion beam to analyze the cause of resistor failure. The results show that there is a crack in the terminal electrode of the film resistor. In addition to the obvious problems such as cracking, the electrode layer also showed sulfide corrosion of the Ag electrode.