The primary objective of this study is to develop equations of the bond stress and relative slippage between fiber-reinforced polymer (FRP) bars and concrete exposed to different temperature ranging from 20°C to 190°C. Equations were established through theoretical analysis and simulation of the bond-slip constitutive relationship between FRP bars and concrete. According to the expressions, the variations of the bond stress and relative slippage between the two diffident materials can be evaluated at different locations. This paper made the analysis based on the theory of elasticity, using a bilinear model. An example to compare the results between experiment and theory had been proposed. It is indicated that the theoretical analysis here is in good agreement with the experimental data in related literature. The results can be applied to fire resistance design of FRP reinforced concrete structures.