Abstract: At three levels of simulated acid rainfall intensities with pH values of 2.5 (severe), 4.0 (medium) and 5.6 (light) respectively, the responses of chlorophyll fluorescence and photosynthetic parameters of Quercus glauca seedlings were studied in three acid rainfall treatments, i.e. only the aboveground of seedlings exposed to acid rain (T₁), both of the seedlings and soil exposed to acid rain (T₂), only the soil exposed to acid rain (T₃) compared with blank control (CK). Under the severe acid rainfall, T₁ significantly inhibited chlorophyll synthesis, and thus reduced the primary photochemical efficiency of PSⅡ (F_v/F_m), potential activity of PSⅡ (F_v/F_o), apparent quantum (Y), net photosynthetic rate (P_n), and transpiration rate (T_r), but increased the light compensation point (LCP) and dark respiration rate (R_d) of Q. glauca seedlings. T₂ inhibited, but T₃ played a little enhancement on the aforementioned parameters of Q. glauca seedlings. Under the conditions of medium and light acid rainfall intensities, the above parameters in the three treatments were higher than that of CK, except with lower R_d. The chlorophyll fluorescence and photosynthetic parameters showed a similar tendency in the three treatments, i.e. T₂＞T₃＞T₁. It indicated that T₁  had the strongest inhibition on seedlings in condition of the severe acid rainfall, while T₂ had the most dramatic facilitating effect on seedlings under the medium and light acid rainfall. Intensity of acid rainfall had significant influences on SPAD, F_v/F_m, F_v/F_o, Y, P_n, T_r and maximum photosynthetic rate (A_max), whereas treatments of acid rainfall affected SPAD, F_v/F_m, Y, P_n, T_r, A_max and light saturation point (LSP). The interaction of acid rainfall intensities and treatments played significant effects on SPAD, F_v/F_m, Y, P_n and A_max.