In order to study the corrosion effect of vitamin corrosion inhibitor in reinforced concrete systems，the effects of thiamine (VitB1), nicotinic acid (VitB3), pyridoxine (VitB6) and ascorbic acid (VitC) on steel reinforcement in simulated pore solutions of concrete containing chlorine was investigated using dynamic potential polarization and electrochemical impedance spectroscopy tests. The mechanism of vitamin corrosion inhibition on steel reinforcement was also discussed based on density general function theory with quantum chemical calculations. The results show that VitB6 has the best corrosion inhibition effect in simulated pore solution of concrete containing 0.05 mol/L NaCl because of the strongest bonding stability between its highest occupied molecular orbital and the 3d orbital of iron. All four vitamins have a specific concentration value to achieve the best corrosion inhibition effect IE. At this time, VitB1 and VitB3 are anodic corrosion inhibitors and VitB6 and VitC are mixed corrosion inhibitors. With the increase of vitamin concentration, the IE tends to fluctuate inversely, which is due to the inhibition of cathodic reaction caused by the adsorption of polar groups on steel surface, further aggravating the imbalance between cathode and anode.