Phosphate based binders are high early strength materials with a short setting time. Usually, they are used as rapid repair material for concrete structures. The feasibility of a basalt fiber reinforced inorganic binder for strengthening concrete was studied. We successfully compounded suitable phosphate binder (PB) for concrete strengthening. In the current paper, phosphate binder was to adjusted to has excellent workability, suitable setting time and fluidity. Compressive strength of phosphate binder mortar, bonding strength between PB and Portland cement mortar, and strengthening effect of PB sticked basalt fiber on concrete beam were measured. Results showed that PB has excellent adhesion with Portland cement mortar. The strengthening effect of basalt fiber reinforced PB composite on concrete beam is evident. It is feasible that concrete strengthening by basalt fiber reinforced inorganic adhesive.