The maintenance effect of steam generator (SG) during lay-up in pressurized water reactor (PWR) nuclear power plants is controlled by the maintenance method, pH, hydrazine concentration and other factors. In this paper, the corrosion immersion test, corrosion morphology observation and Raman spectroscopy methods are utilized to investigate the deoxidization effect of different working conditions on the key materials of the SG (Q245 carbon steel, 18MnD5 low alloy steel and 690TT nickel-based alloy) under the simulated maintenance condition of SG during shutdown. The results indicate that: (1) The corrosion rate of specimen under dry lay-up is relatively low compared with that under wet lay-up. The corrosion rate of Q245 and 18MnD5 under 80% RH air static condition is close to zero; under the condition of SER water spraying, the corrosion rate of Q245 and 18MnD5 is close to 4.32 μm/year and 8.75 μm/year respectively, both of which are lower than the corrosion rate in condition of wet lay-up (75 mg/kg hydrazine). (2) Reducing either hydrazine concentration or pH during wet lay-up increases the uniform corrosion rate of carbon and low alloy steels, while the uniform corrosion rate of nickel-based alloys is basically lower than 1.5 μm/year. (3) The limit of hydrazine concentration can be lowered from 75 to 25 mg/kg if nitrogen overlay is used and pH is maintained at 9.8 or above. (4) Without nitrogen overlay, if the pH value is kept above 10.0, 25 mg/kg hydrazine already has significant maintenance effect, relative to the SER water maintenance condition to reduce the corrosion rate of nearly 60%. The maintenance effect of 75 mg/kg hydrazine is better, relative to the SER water maintenance condition to reduce the corrosion rate of nearly 80%.