Abstract: he corrosion behaviors of 304L and 321 stainless steels in simulated solution of MIPR were studied. The results show that both of stainless steels perform perfect uniform corrosion resistance and no intergranular corrosion and stress corrosion cracking at obtained conditions. It is due to a compact Cr₂O₃ film occurred on the sample surface of stainless steels, which plays a role in hindering corrosion development. The synergistic effect of inner and outer films improves the corrosion resistance of stainless steels.