To predict the effect of microorganisms breeding in cutting fluid on the corrosion of 2219 aluminum alloy(AA 2219)used in aerospace,the corrosion rate of microorganisms in cutting fluid on 2219 aluminum alloy was analyzed by weight loss method.The adhesion of microorganisms on the surface of 2219 aluminum alloy was observed by inverted fluorescent microscope.The corrosion morphology of products and the corrosion profile after removing corrosion products were observed by scanning electron microscope(SEM)and white light interferometer,respectively.The elements of surface corrosion products were analyzed by energy dispersive spectroscopy(EDS),and the corrosion mechanism was studied by electrochemical impedance spectroscopy(EIS).The results indicate that the microorganisms in the cutting fluid adhere to the surface of 2219 aluminum alloy to form uneven corrosion product film and biofilm.The presence of microorganisms increase the corrosion rate of 2219 aluminum alloy by 59%.After removing the surface film,obvious pitting pits are found,and the maximum depth is 9.96 μm.The electrochemical results also show that the charge transfer resistance of aluminum alloy immersed in cutting fluid with microorganisms decreases and the corrosion rate increases significantly.The microorganisms in the cutting fluid accelerate the corrosion of 2219 aluminum alloy obviously,and pitting corrosion is the main form of corrosion.