Abstract: Taking the seedling of Atractylodes lancea as the experimental material, the pot experiment of simulated illumination stress soil was carried out under different light conditions（CK 18.26%-36.04%,T1 51.10%,T2 80.73%,T3 100%）,photosynthetic fluorescence parameters and net photosynthetic rate of leaves of Atractylodes lancea were measured 20 days later, in order to reveal the adaptive mechanism of light on photosynthetic fluorescence of Atractylodes lancea.The reseults showed that the values of net photosynthetic rate（Pn）,transpiration rate（Tr）,real photochemical quantum efficiency（PhiPS2）,photochemical quenching coefficient（qP）,electron transfer efficiency（ETR）,instantaneous water use efficiency（WUE） and photochemical quantum efficiency（Fv/Fm） increased and then decreased with the increase of illumination intensity.The values of intercellular CO₂ concentration（Ci） and non-photochemical quenching coefficient（NPQ） were reversed.The order of relationship between Pn value and PAR increase to the highest point was T1＞T2＞CK＞T3.In conclusion, when the light intensity reached 100%,the photosynthetic efficiency of Atractylodes lancea was severely inhibited.