The corrosion characteristics of prestressed steel bars are the basis for studying the durability failure and prevention of prestressed concrete structures. Therefore, two methods, internal salt addition and external salt immersion, were used to conduct comparative tests on the corrosion of steel bars in three groups of concrete under natural climate conditions: steel strand and hot-rolled ribbed steel bars, steel strand and hot-rolled plain round steel bars, steel strand center steel wire and hot-rolled plain round steel bars. Through testing the corrosion current density during the corrosion process and comparing and analyzing the broken shape observation and weighing after the experiment, the following results were obtained: the degree of corrosion on the outer surface of the steel bar is significantly more severe on the side facing the protective layer than on the side facing the protective layer; The corrosion on the outer surface of the steel strand and its central steel wire is relatively uneven, with severe local corrosion - pit corrosion morphology, followed by ribbed steel bars, and smooth round steel bars are relatively the most uniform and comprehensive; The internal surface of the steel strand undergoes relatively comprehensive and uniform corrosion similar to that in air; The average external surface corrosion rate of steel strands is lower than that of hot-rolled ribbed steel bars and hot-rolled plain round steel bars, but severe local corrosion is extremely detrimental to their tensile performance. In addition, electrochemical mechanism analysis was conducted on the above corrosion characteristics