For the evaluation of damage to a structure after exposure to fire, the residual mechanical properties of structural materials need to be evaluated first. Many factors can affect the post-fire behavior of structural and reinforcing steels. In this paper, existing test data are collected from an extensive survey of the literature. A statistical analysis is conducted to analyze the effects of heat exposure on key parameters, such as the residual modulus of elasticity, residual yield strength, and residual ultimate strength, which control the full-range stress-strain curves of steel. A simplified stress-strain model is developed, which can be used for both structural and reinforcing steels after heating and cooling down to room temperature.