In order to get the method of alleviate salinity damage to Coptis chinensis Franch.under salt stress,we used exogenous 5-aminolevulinic acid(ALA) in the experiment.Several physiological indexes like the contents of photosynthetic pigment,chlorophyll fluorescence and photosynthesis parameters.of C.chinensis were measured treated by ALA under salt stress(NaCl with the concentration of 100 mmol·L^-1).The study results indicated that:(1)The exogenous ALA obviously increased the contents of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoids.(2)The levels of P_n,G_s,and T_r of C.chinensis seedlings were all decreased with the increased concentrations and treatment days under salinity stress,and the value of C_i increased with the opposite tendency.These results indicate that the main influencing factor to the decreasing net photosynthetic rate of C.chinensis is non-stomatal factors.(3)After treated with different concentrations of exogenous ALA,the P_n,G_s,and T_r were all increased with different degrees,and the level of C_i was decreased.(4)ALA applied in the experiment also increased maximum fluorescence(F_m,1.234),photochemical efficiency of photosystem II(F_v/F_m,0.849),photochemical efficiency(F_v′/F_m′,0.685),PSⅡ actual photochemical efficiency(Φ_PSⅡ,0.545),photochemical quench coefficient(q_P,0.872),decreased the levels of minimal fluorescence(F₀,0.211) and non-photochemical quenching coefficient(NPQ,0.251).As can be seen,ALA with the appropriate concentration of 50 mg·L^-1 could significantly alleviate the damage of salt stress to C.chinensis,reduce excess excitation dissipation and improve photochemical electron transport efficiency and efficiently protect from PSⅡ damage.ALA obviously promoted the salt resistance of C.chinensis under salt stress.