Abstract: That stress corrosion cracking (SCC) is belong to hydrogen induced cracking (HIC) or the anodic preferential dissolution can be solved based on a synthetical study using the following methods, i.e, electrochemistry, the activation energy, the effect of loading modes, comparing the threshold value, initiation site and fracture of SCC to these of HIC, cracking initiation under compressive stress and the correlation between the local plastic deformation and crack nucle-ation. During SCC of austenitic stainless steel in MgCl2 solution, hydrogen can enter into the specimen and enrich and then facilitate the anodic dissolution but does not control the SCC, therefore the mechanism of the SCC is belong to the anodic dissolution. The effects of hydrogen and stress on anodic dissolution are synergistic rather than simply additive. The normal stress instead of shear stress pays a controlled role in SCC of anodic dissolution.