Knowing the correct corrosion mechanism of Alloy 690 is valuable for corrosion protection of equipment. Considering the semiconductor characteristics of metal oxide film on the corrosion surface, a new corrosion dynamics mechanism was proposed based on the quantum mechanics. At first, the nature and characteristics of currents were analyzed in different applied potentials by the band structures of metal. Then the relationship between corrosion potential and current was developed and the kinetic mechanism of corrosion was explained from microscopic view. The results show that the corrosion process is controlled by four kinds of electron transfer named generation-compound, diffusion, tunneling and avalanche in the interface of solution, oxidation film and metal. It is reasonable to interpret the polarization curve of Alloy 690 by quantum mechanics because this relationship has very good consistency with that of experiments