Abstract: The objective was to understand the corrosion behavior of the Ge antireflection coating in Aspergillus niger, provide data support for the development of novel protective film systems and the anti-mold design of optical systems, and improve the environmental adaptability of infrared materials. The method was to study the corrosion behavior and influence law of Aspergillus niger on the Ge antireflection coating samples via fungus-accelerated tests using fluorescence microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results demonstrated that Aspergillus niger is an acid-producing microorganism; in the stable phase, its biomass was the highest, and the accumulation of cell metabolites peaked. In the logarithmic growth phase, it caused significant changes in the pH value of the growth environment, which increased environmental acidity. Carbon was adsorbed on the surface layer of the Ge antireflection coating, then the Aspergillus niger used it as nutrition to adhere to the surface of the sample, and multiply on its surface, thereby consuming the carbon content of the surface. With the proliferation of Aspergillus niger, the pH of the sample surface also decreased, and the metal elements on the sample surface were oxidized and gradually dissolved. The Ge and Zn on the surface of the Ge antireflection coating sample were successively peeled off. After participating in the reaction, the surface morphology of the sample was severely damaged and a large number of corrosion pits were formed. It was inferred that the corrosion behavior of Aspergillus niger on the Ge antireflection coating samples was mainly pitting corrosion, and that growth metabolism promoted the corrosion of antireflective coatings.