This study investigated the effect of hot-dip aluminum on the life duration of low carbon steel, and the mechanism of failure mode of aluminized layer under constant load in hot corrosion environment with a portion of 50/50 mixture of NaCl and Na_2SO_4. The specimens were made from SPHC with the thickness about 2 mm, and hot-dip aluminized for 120 seconds. The constant tensile test was performed by hanging specimens covered with 2 mg/cm^2 salt mixture under constant load in a tube furnace at 750℃. The results show that the aluminized specimens have higher elongation and longer lifetime than bare steels'. The fracture analyses and microstructure analyses of the aluminized specimens show that the aluminized layer can provide steel to having grain growth without corrosion which also can increase the creep resistant. The FeAl and FeAl_2 phases have good adherent to the substrate while aluminized layer cracked, which can offer steel sufficient time to do stress relaxation by recrystallization and deformation. According to the result of this study, it has been confirmed that the lifetime of steels in hot corrosion under constant load can be remarkably improved by hot-dip aluminizing process.