Influences of temperature and relative humidity on the control mode and rate of reinforcing steel corrosion were investigated by combining the theoretical analysis, numerical simulation and experimental data. First, the anodic corrosion potential in the traditional macro cell corrosion model was improved by taking into account the influence of reverse reaction rate on the activation polarization over potential and based on the principle of electrochemical corrosion. Then the influences of temperature and relative humidity on the various electrochemical parameters, such as the equilibrium potential, exchange current density and limiting current density, were discussed; mean while, an improved macro cell corrosion model of reinforcing steel embedded in concrete was developed which takes into account the temperature and relative humidity. Finally, the applicability and efficiency of the developed model were validated by comparing with the experimental data of both artificially accelerated and natural corrosion experiments; furthermore, the influences of temperature and relative humidity on the control mode and rate of reinforcing steel corrosion were investigated.