Abstract: In order to explore the photosynthetic response characteristic of bamboos to the high frequency of acid rain stress, the relative content of chlorophyll, the diurnal variation of photosynthesis and chlorophyll fluorescence in the leaves of Pleioblastus fortunei, an ornamental bamboo species were determined by foliar spraying with simulated acid rain(SAR)in different intensity of pH(2.0,3.0,4.0). The results showed that treating with different intensity of SAR could result in the decrease of the relative content of chlorophy. The lower was the pH value, was the greater the decrease. The acid rain stress led to diurnal variation changing from the control “single peak” to “bimodal”, which present obviously photosynthetic depression at midday. With the increase of stress intensity, net photosynthetic rate(P_n), stomatal conductance(G_s), transpiration rate(T_r)and stomatal limitation(L_s)decreased. while, the increasement of the intercellular CO₂ concentration(C_i)indicated that the decline of photosynthetic rate was mainly caused by non-stomatal limiting factor under acid rain stress. In addition, the determination of fluorescence parameters showed that SAR of different intensity made PSⅡ photochemical efficiency(F_v/F_m), the largest PSⅡ activity of potential(F_v/F_o), PSⅡ photochemical efficiency(F_v'/F_m'), PSⅡ photochemical efficiency(Φ_PSⅡ), photochemical quenching(q_P)significantly lower, but the non-photochemical quenching(NPQ)was significantly increased. After the recovery of a month, the fluorescence parameters of P.fortunei under pH 4.0 treatment could mostly recover; However, all of P.fortunei under pH 2.0 can't recover. It shows that P. fortunei treated with SAR of pH 4.0 has a strong ability to repair itself, but with pH 2.0, it can't recover through self-regulation. The enhancement of NPQ in P. fortunei might be a vital mechanism for the resistence to light under the acid stress.