Abstract: Experiments were carried out to test the alkaline resistance properties of basalt fibers and their effects on the mechanical property of fiber reinforced concrete. Mass loss rates of fibers were weighed after being soaked at different aqueous alkali and at different temperatures respectively. Meanwhile, mechanical properties of basalt fiber reinforced concrete (BFRC) were tested with three different volume fractions of basalt fiber. Microphotographs of corroded fibers show that as alkalinity and curing temperature increase, the scaling of fiber appeares even worse. However, mechanical properties of BFRC at the early age are close to those of the reference while compressive strength and flexural strength of BFRC at 28 d are deeply lower than those of the reference. Microstructure images of basalt fiber in concrete appeare to be corroded seriously. The results show that instability of basalt fiber in alkaline solution may impact the mechanical property of BFRC.