The seasonal changes of light response curve and photosynthetic characteristics of Osmanthus fragrans var.semperflorens were determined by LI-6400.The results showed that the light response curve changes of O. fragrans var.semperflorens's leaves at different seasons were similar.The net photosynthetic rate and light compensation point were Jan< Apr< Oct< Jul,and the light saturation point was Jul< Oct< Apr< Jan.The day changes of Pn,Tr,VPD and Gs of O. fragrans var.semperflorens were single peak curve separately at January and April,while double peak curve and had photosynthetic "lunch-break" atmosphere at July and October.The seasonal change of Ci was that Ci decreased continuously at January,while decreased first and then reached a small peak value at 15:00 at April,and appeared the lowest point at 10:00 and the highest point at 15:00 at July and October.