The microbiologically influenced corrosion of CoCrMnNi high entropy alloy induced by P. aeruginosa was investigated in this work. The results of electrochemical tests, time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy showed that the thickness of passive film was significantly decreased in the presence of P. aeruginosa and the corrosion of HEA was accelerated. When the organic nutrients were deficient, the extracellular electron transfer process was promoted and the corrosion resistance of the HEA was further decreased according to the results of potentiodynamic polarization and Mott-Schottky. The effect of nutrients deficiency on MIC acceleration was more prominent after the degradation of the passive film. Mn metal in the HEA substrate preferentially participated in the bacterial metabolism as an alternative energy source due to the high activity.