Abstract: The tension stiffening effect is the premise of accurate evaluation of the deformation and crack width of fiber reinforced polymer composite (FRP) bar/concrete members. An analytical method for determining the deformation of FRP bar/concrete tension member was proposed. A simplified four-linear model based on the modified Eligehausen model (modified BPE model) was presented. The distribution of stress, displacement of FRP bars and concrete and the distribution of bond force, slip between bars and concrete were established. By combining with the cracking criterion of concrete, an algorithm for the deformation of FRP reinforced tensive ties at different loading stages was proposed. After verification by comparing with experimental data in the literature, the effects of different parameters on the tension stiffening were analyzed. Parametric analysis results indicate that concrete strength and reinforcement ratio of FRP bars have a minor impact on the tension stiffening effect. However, the elastic modulus of FRP bars dominates the tension stiffening behavior of FRP reinforced concrete tensile elements.