Abstract: In order to reveal the effects of high temperature stress and recovery on photosynthetic characteristics and photosynthetic pigment content of greenhouse chrysanthemum leaves, taking the seedlings of ‘Jinbeidahong’ as the experimental material, the experiments of high temperature and durations were carried out in a large artificial climate chamber with the daily minimum temperature/maximum temperature as 25 ℃/35 ℃,30 ℃/40 ℃,and durations as 3,6,9,12 days respectively, then recoverd at 20 ℃/30 ℃ which been taken as control check（CK） for 5,10,15 days.The photosynthetic parameters and photosynthetic pigment content of greenhouse chrysanthemum leaves with different treatments were determined in seedlings stages.The results showed that when the daily maximum temperature was above 35 ℃,all the indexes for the light saturation point（LSP）,apparent quantum efficiency（AQE）,net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,stomata limitation（Ls）,water use efficiency（WUE）,chlorophyll content and carotenoid content of greenhouse chrysanthemum leaves decreased with the increase of temperature and duration.When the daily maximum temperature reached 40 ℃,all the values were 56.42%,41.22%,78.54%,90.33%,54.55%,31.29%,54.09%,42.44% and 40.26% lower than that of the CK,respectively.After recovery, each index increased to some extent, but it could not recover to CK level after stabilizing.After 15 days recovery, the parameters were 47.04%,35.88%,50.56%,76.52%,33.84%,19.45%,32.75%,23.90% and 23.07% lower than CK.This study revealed high temperature stress seriously inhibited the growth of chrysanthemum seedlings and caused irreversible damage to the structure and function of the light system of chrysanthemum seedlings.