Basalt fiber composite reinforcement is widely used in anchoring engineering due to its high strength and good durability. Therefore, the expansive clay site is taken as an example, while anchor bolt support of basalt reinforcement, steel anchor bolt support of basalt reinforcement and unsupported anchor bolt are carried out respectively by excavating three slopes, and the support effects of different supporting structures in expansive soil slope site are discussed. The results show that the reinforcement anchor bolt and basalt reinforcement anchor bolt are under less stress, the deformation of the slope after reinforcement is small, and the overall stability of the slope is stable. When the foot of the slope is excavated and immersed in water, the force of the anchor bolt increases suddenly, and when the top of the slope is continued to be immersed in water, the force of the anchor bolt increases significantly and the rate of change is large. The research results can provide a design basis for the use of basalt fiber composite reinforcement to replace the existing reinforcement in slope engineering such as anchor bolt (cables) and supporting piles.