Abstract: In order to explore how temperature and light directly affect photosynthesis，the chlorophyll fluorescence was investigated in tree peony（Paeonia suffruticosa‘Roufurong’）leaves treated with different temperatures（15，20，25，30，35 and 40 ℃）coupled with different light intensities（100，700 and 1 400 μmol · m-2 · s-1）. The results indicated that with the increase of light intensity，the maximal photochemical efficiency（Fv/Fm），the actual quantum yield of photosystem Ⅱ（ΦPSⅡ），the efficiency of excitation capture of open PSⅡ center（Fv′/Fm′）and the photochemical quenching（qP）reduced significantly and those under 1 400 μmol · m-2 · s-1 treatment exhibited the lowest. Compared with 25 ℃，the chilling treatment（15 ℃）and the heat treatment（40 ℃）caused dramatic decrease in Fv/Fm，ΦPSⅡ，Fv′/Fm′ and qP. Meanwhile，with the increase of light intensity，the allocation of excited energy to PSⅠ 　　 declined significantly，and the allocation to PSⅡ increased significantly，which caused a serious imbalance of excited energy distribution. According to the results，high temperature and strong light stress led to a tremendous increase in the non-photochemical quenching（NPQ），however，more of the excessive radiative energy absorbance was not completely dissipated. Besides this，serious imbalance of excited energy distribution was observed under high irradiance and more excitation energy was allocated to PSⅡ，which led to an increase of excitation pressure of PSⅡ（1–qP）and accelerated the damage of PSⅡ.

Key words: tree peony, photosynthesis, photoinhibition, chlorophyll fluorescence parameter, light and temperature treatment