Abstract: The fiber reinforced polymer (FRP) bars have the behavior of strong corrosion resistance, high tensile strength and small elastic modulus, and can be used to replace steel bars, which undergo wearing due to rusting in slope reinforcement. The pre-stress FRP bars are reasonable, but the bars have low shear strength and cannot be pre-stressed using the traditional rigid clamp, lest they are crashed to failure. An end anchoring pre-stress locking device is designed for pre-stress application and retention in the FRP bars. Field tests are conducted to verify the stability of the device. The test results show that the device is practically feasible and convenient, and it can apply and retain pre-stress in basalt-glass fiber reinforced polymer (B-GFRP) bars well. Exposure to external factors such as heavy rains and blasting results in the loss of pre-stress. The pre-stress loss is caused by degeneration of the bonding resulting from external factors, but not by the invalidation of the device. The pre-stress retention by the device in the B-GFRP bars is 5%~35%, which conforms to the control criterion for the pre-stress loss of the steel pre-stressed soil nail reinforcement.