The deterioration of concrete materials in the sewage environment is prominent, significantly shortening the structure's service life. Based on the composite modification method, modified basalt fiber high-durability concrete is proposed to solve the problem of insufficient material durability in the sewage environment. The acid environment erosion test was carried out for the modified concrete materials. The macroscopic performance indexes were obtained, such as apparent corrosion characteristics, water absorption rate and compressive strength. The corrosion mechanism and deterioration law of concrete materials under an acid environment were revealed by combining the analysis of the fine structure and corrosion product composition. The results show that the hydration reaction of the modified concrete was adequate. The generation of C–S–H gel and Ca(OH)2 increased significantly. The porosity was reduced by 40%, and the initial strength was increased by 12%. After 240d corrosion, the strength of ordinary concrete was degraded by 41%. The degradation rate of modified concrete was 26%, its residual strength was 1.4 times that of ordinary concrete, and its corrosion-resistant ability was greatly improved. Based on the experiment, the corrosion resistance mechanism analysis was carried out, and it was found that the inorganic aluminium salt compound salt crystal expansion modification effect is better than the sodium methyl silicate reticulated resin film modification. However, after double doping, the corrosion resistance is reduced instead, and it is recommended that inorganic aluminium salts be preferred as anti-corrosion and anti-seepage adding materials. The research results of this paper can better enhance the acid environment erosion resistance of concrete, engineering application prospect is good. •Put forward the concept of composite modified anti-corrosion.•The mechanism of new concrete protection under an acidic environment was revealed.•New technology for corrosion protection of sewage environmental engineering.