Abstract: Corrosion behavior of HRB400A steel reinforcement whose essential composition was 0. 45% Cr-0. 38% Cu-0. 11% P(by mass) used for 1,2,and 3 a in plateau area,including corrosion rate,macroscopic appearance,cross-sectional micrograph,and components of corrosion products,was investigated by camera,scanning electron microscope,X-ray diffractometer,and weight-loss method,and compared with those of HRB400 steel reinforcement without chromium and copper elements. The results showed that(a) HRB400 and HRB400A steel reinforcements all exhibited microstructure consisting of ferrite and pearlite and largely the same mechanical properties;(b) the corrosion mass-loss of HRB400A steel reinforcements used for 1,2,and 3 a in plateau area was respectively 42%,8%,and 14% less than that of HRB400 steel reinforcements used for the same lengths of time;(c) the plateau atmosphere had no evident influence on density and phase structure of the corrosion products on HRB400A steel reinforcement,and the corrosion products on HRB400 and HRB400A steel reinforcements were denser,and mainly composed of α-FeOOH and γ-FeOOH.