Atomic force microscope (AFM) was used to study in situ the change in slip bands during stress corrosion of brass in the ammonia solution prior to initiation of stress corrosion crack. The result showed that additive slip bands appeared ahead of a loaded notch tip during stress corrosion prior to initiation of stress corrosion crack after the constant deflection specimen was precrept for 48 h and then polished. The average height and spacing of slip bands generated during stress corrosion were about three times less or larger, respectively, than those during loading in air.