Abstract: The anticorrosivity and microstructure of 0Cr17Ni4Cu4Nb steel in artificial seawater after different heat treatment processes were investigated by electrochemical methods, such as polarization and cyclic polarization curves. The results indicated that if a modification follows the solution treatment of 0Cr17Ni4Cu4Nb steel before aging treatment, the steel structure will become finer and more homogeneous with the breakdown potential, width of passivation zone and protection potential all enhanced obviously. Thus, the anticorrosivity of the steel in seawater will be entirely superior to the steel without the modification. The modification and changes in its parameters will result in the variation of the quantity and sorts of carbide precipitates during heating, thus affecting the microstructure and anticorrosivity of the steel.