This paper covers increase in tower crane steel structure. Q235 steel structure is galvanized by solution without ammonia or cyanogen and is passivation treated. Corrosion resistant tests of samples that have been used for 4 years are carried out in acid salt fog and corrosion resistant capability of the samples is forecasted based on non - equidistance grey forecasting theory. Results reveal that this kind of forecasting method features high accurate and corrosion resistant capability of steel structure has been inmproved gr...