Abstract: The Potential vs time curves of reinforcing steels embedded in fresh concrete mud containing trace amount of Cl^- have been measured by galvanostatic method with anodic current density of 50μA/cm². The effect of 7 kinds of additives (water reduced agent, fast strengthening agent, inhibits solidifing agent and high performance water reduced agent, et al) on electrochemical behavior of the embedded steels in low concentration of Cl^- has been investigated. The results show that the correct and effective testing method in the Standard JC 475-92 is proved,and trace amount of Cl^- is detrimental to the passivity of the steel tendon embedded in concrete. The additives tested are beneficial to inhibition the breaking up of passive film by Cl^- for reinforcing steels embedded in fresh concrete mud.