The anode polarization curve of A0 pure aluminum in DI (de-ions) water was measured to simulate the pit corrosion of reactor pool shell. It confirmed the A0 aluminum is easy to passivate in DI water. The potential in the pit were determined with EG&G Princeton Applied Research Potentiostat/ Galvanostat Model 273, the polarization curve shows that the simulated corrosion pit was in passivated situation, even if the oxidization film was broken, the corrosion pit will probably develop slowly, the varied pH in pit was determined with pH measurer, and the working curves were obtained, which shows the obvious acidification exists in pit for the sample with oxidization film. The service life of A0 aluminum pool shell was estimated.