Abstract: In order to explore the effect of high temperature stress on energy supply and photosynthetic rate in the leaves of Agrostis stolonifera L. “Yuexuan 1” and its parents, the plants were treated by heat stress with 35/30℃ (day/night) for 0, 12, 24, 36, and 48h. After the experiments, the fully expanded leaves were collected and measured. The results showed that the contents of ATP, ADP, AMP and the value of energy charge were higher in the leaves of "Yuexuan 1" than its parents during the whole treatment process. The activities of RuBPcase and chloroplast ATPase, the photosynthetic rate and the oxygen-evolving rate were also higher than those of its parents during the high temperature stress treatment. It could be concluded that "Yuexuan 1” had better heat stress tolerance and kept higher rate of photosynthesis than its parents, which may result from lager amount of ATP supply from its leaves.