Abstract: In this study, various artificial acid rain environments were simulated in the laboratory. The reinforced concrete beams and CFRP-reinforced concrete beams were tested after being exposed to artificial acid environments for certain periods. Three-point bending tests were performed to investigate surface crack initiation/propagation of concrete beams. The results indicate that fractal theory can be used to describe the crack of CFRP-reinforced concrete beams. Relationship between fractal dimension and mechanics performance parameters of concrete beams (i.e., damage depth, concrete strength, frequency, ultimate carrying capacity, ultimate deflection, displacement ductility factor) was discussed. It is illustrated that crack fractal dimension decreased with the increase of damage depth. It is found that fractal dimension of CFRP-reinforced concrete beams was larger than that of reinforced concrete beams exposed to the same acid environment. The linear relationship was found between fractal dimension and ultimate carrying capacity of CFRP-reinforced concrete beams. Therefore, the fractal dimension of surface crack could be used to estimate the damage degree of CFRP-reinforced concrete flexural member. These results can provide an effective reference for the evaluation of carrying capacity and service life of the in-service concrete structures.