The combination of basalt fiber reinforced polymer (BFRP) confinement and coal gangue concrete (CGC) is an economical and innovative approach for serving as a supporting structure in the underground mine. Nevertheless, the sulfate-rich mine water and mist exist in the mine environment, which may cause the performance deterioration of structures. Thus, the long-term behavior of BFRP-confined CGC in the sulfate-rich environment was systematically explored, based on the sulfate durability investigation of BFRP sheets and CGC. The tensile test of BFRP sheets and the compressive test of CGC were first carried out to evaluate their deterioration laws and mechanism in different sulfate environment. More importantly, axial compression test of FRP-confined concrete cylindrical specimens after sulfate attack were conducted, considering the effect of inner concrete, FRP layer, sulfate concentration and corrosion time on the stress-strain response and dilation properties. The results indicate that the tensile strength of BFRP sheet declined to a small extent with the extension of sulfate corrosion due to the degradation of epoxy resin and matrix-fiber interface. Additionally, the compressive strength of CGC exhibits a first increase and then decrease trend as the secondary hydration occurs and the sulfate ions react with the hydrated production to form expansive gypsum and ettringite crystals. The strength and ductility of CGC were improved by FRP confinement regardless of sulfate attack or not, whereas sulfate corrosion degraded the improvement ratio, especially the deformation capacity. Most importantly, the sulfate degradation coefficients were introduced into ultimate strength and strain models for sulfate-attacked BFRP-confined CGC, providing a basis for its design and life cycle assessment in the underground mine.