Abstract:Merremia boisiana （Gagnep.） V. Ooststr. （Convolvulaceae） is an invasive plant that newly appeared in a forest plantation near Guangzhou. The photosynthesis characteristic observed by using chlorophyll fluorescence technique in this plant was examined under different actinic lights, and the light utilization was measured in detached leaves under different stress of low or high temperatures and dehydration. The results showed that the chlorophyll fluorescence parameters Fv＇/Fm＇, qP and ΦPSⅡ decreased with the increase of actinic light intensity, but qN and NPQ increased. When detached leaves were treated for 6 hours at 5 ℃, the Fv＇/Fm＇, qP and ΦPSⅡ were higher than those at 25℃ and 45℃. However, if detached leaves were treated for 6 hours at 5℃ and 45℃, the NPQ was evidently lower than those at 25℃ （control）, and the qN reduced a little. Being dehydrated for 12 hours, the detached leaves still had certain ability of light energy conversion. Whereas the values of qP, ΦPSⅡ, qN and NPQ were significantly decreased after the leaves were dehydrated for 24 and 36 hours. It is shown that Merremia boisiana has strong adaptability to different light intensity, temperature and water conditions, which may be an important cause of its rapid dispersal in forests.