This study investigated the corrosion behavior and mechanism of aspergillus versicolor on PCB-Cu under constant magnetic fields of different strengths. The surfaces of the PCB-Cu samples were sprayed with a spore suspension, and magnetic fields of different constant strength were applied along the direction perpendicular to the surface of the sample. The growth of aspergillus versicolor and the corrosion behavior of PCB surface were studied by using 3D confocal microscope, scanning electron microscope (SEM), energy spectrum analysis (EDS), and Raman spectroscopy. The potential change on the PCB-Cu surfaces were characterized by scanning Kelvin probe (SKP). By observing the surface morphology of the mold, it could be clearly seen that the molds in the non-magnetic field group had more vigorous life activities, and the higher the magnetic field strength, the stronger the inhibitory effect on mold growth, which reduced the number of mold spores and deteriorated the growth status. The magnetic field affects the growth of mold and the migration of corrosive ions, and the corrosion inflection point appears when the strength is 15 mT. The composition of the corrosion products were different, where the content of O and Cl in the non-magnetic field were higher than that in the magnetic field. The magnetic field mainly inhibits the corrosion of PCB-Cu by affecting the growth of mold, but the magnetic field also affects the migration of ions to accelerate the electrochemical corrosion. Therefore, when the magnetic field strength is 15 mT, the degree of corrosion is minimal. The corrosion products without magnetic field are mainly composed of CuO, a small amount of Cu2O and copper chlorides, but CuO and copper chlorides become the main corrosion products after applying a magnetic field.