Abstract: Different plants have varied physiological characteristics，thus their irritability to light is also different. Therefore，plants form unique light requirements to adapt themselves to their own growth during evolution. Photosynthetic index and leaf green fluorescence parameters of Ophiopogon japonicus（L.F.）Ker-Gawl leaves were measured by LI-6400XT portable photosynthesis analyzer under 5 light intensity treatments（light transmittance of 95%，72%，48%，24%，and 8%）. With the increase of relative light intensity，the apparent quantum yield（AQE）presented the trend of first increase and then decrease with the increase of light intensity. O. japonicus（L.F.）Ker-Gawl leaf pigment content and initial fluorescence intensity（F0）increased. Chlorophyll ab value was also in the trend of first increase and then decrease. Fluorescence parameter PSⅡ maximum light energy conversion efficiency increased. The actual PSⅡ photochemical efficiency（ΦPSⅡ）under the action of light，PSⅡ effective photochemical quantum efficiency（Fv’/Fm’），electron transfer rate（ETR），and pho-tochemical quenching coefficient（qP）% had a rising trend under the relative light intensity of 72%-48%. Under the relative light intensity of 72%-48%，the response of O. japonicus（L.F.）Ker-Gawl to PSⅡ was stronger，which was conducive to the growth and development of O. japonicus（L.F.）Ker-Gawl. Therefore，appropriate shade measures should be employed in large-scale cultivation of O. japonicus（L.F.）Ker-Gawl.

Key words: Ophiopogon japonicus（L.F.）Ker-Gawl, shade, photosynthetic rate, chlorophyll fluorescence