Based on the pitting corrosion characteristics of corroded deformed steel bars embedded in concrete structures in chloride environment, the Finite Element fine Model is established by the ANSYS FE software, and nonlinear analysis was conducted for the influence of corrosion pit on the resistance properties of steel bars. Results show that the effect of pit location is apparent on the mechanical properties of deformed steel bars. The influence of the corrosion pit located at the transverse rib is a little, the second at the longitudinal rib, the most serious at the base circle. The effect of the width and depth for the corrosion pits at the base circle is studied on the relation curves of force and deformation for steel bars, and it is established for the relational expression of the critical width and depth at the disappearance of the yield step on the curves.