This study aims to investigate the nonlinear fluid flow characteristics of fractured granites treated by chemical corrosion under confining pressure conditions. The granite samples with pre-existing fractures underwent chemical corrosion treatment with a pH = 1~12 and corrosion durations of t = 5 ~100 d ays. The nonlinear fluid flow tests were conducted under confining pressures σ = 0 .5~20 M Pa. T he results revealed that the pressure difference (-ΔP) between the inlet and outlet increased with the increment of flow rate, while it decreased with increased σ. When pH = 1, -ΔP for the samples with t = 100 d ays of corrosion was 25% higher than that treatment with t = 5 days. When pH = 3 or 7, -ΔP for the samples with t = 100 days was approximately twice that of the samples with t = 5 days. W hen pH = 12, -ΔP for the samples with t = 100 d ays was the same as that after treated with t = 5 days. The critical hydraulic gradient (J_c) that quantifies the onset of nonlinear fluid flow remained relatively constant when pH = 7, but it exhibited significant fluctuations when pH = 1, 3, or 12. The permeability (K) decreased with increasing σ, and t had the most pronounced impact in neutral conditions. Predictive equations for J_c and K following chemical corrosion treatment were proposed and compared to experimental data, demonstrating a good fit between the two sets and verifying their validity. This study can provide criteria for quantifying fluid flow states and can accurately estimate the hydraulic properties of rock masses treated after chemical corrosion.