Considering the common load bearing features of free section and anchoring section of the prestressed anchor bolt and using the double broken line model, which can present the damping properties of the soil-bolt surface strength, the analytical solutions between bolt resistance force and displacement was obtained based on the load transfer theory. Engineering example analysis verified the correctness of the theoretical derivation. The calculation results indicate that the stiffness and strength of the prestressed bolt are improved when the bearing capacity of free section is taken into account. The calculation results also show that the bearing capacity of the whole bolt increases, but the stiffness decreases on the contrary, while the free section length increases. So it is important to determine the rational length of free section in prestressed anchor bolts design and construction.