Abstract: The basalt fiber(BF)was treated using three coupling agents(KH550, KH560 and KH570),and the comparisons were taken with BF without any treatment. XPS results show that silicon on the surfaces of BF reacts with the silicon on the three coupling agents to form Si—O—Si bonds, and the order of amount is KH550>KH570>KH560. The results from the bending performance and interlaminar shear strength(ILSS)as well as the SEM observations of different BF/EP before and after water bathing show that the treatments of BF with coupling agents can improve the interface bonding properties of BF/EP with the order of KH550>KH560>KH570. SEM observations show that BF and epoxy combined tightly after the treatment by coupling agents, and the interface do not debond when specimen was damaged. The main damage occurs in the matrix, which shows the mechanical properties of the interface are better than that of matrix. The mechanical properties of different BF/EP decline after water bathing, and water resistance is poor. The interface of fiber and matrix debonds, and some fibers are pulled out from the matrix and holes were left in the matrix. The failure mode is a brittle fracture.