Influence of internal temperature and humidity in concrete on rebar corrosion was studied through accelerated carbonation test. The influence degree was expressed by temperature and humidity influence function, and the related rebar corrosion rate model was established. The results show that parameters of the temperature influence function for different kinds of concrete varies quite greatly. However, for the same kind of concrete, parameters change little even though rebar corrosion has different degree. For humidity influence function, parameters are similar not only between the different kinds of concrete, but also for the different degree of rebar corrosion. So the humidity influence function can be expressed by uniform formula. Based on the test results, a new real time dynamic method of rebar corrosion prediction for practical engineering was proposed and discussed.