Abstract: Using one-year-old cutting seedlings of three aromatic plants （Cymbopogon citratus，Melissa officinalis，Rosmarinus officinalis ′Severn Sea′）as experimental materials，contents of chlorophyll， the relative electrical conductivity， activities of superoxide dismutase（SOD），malondialdehyde（MDA），soluble sugar and soluble protein in leaves were measured and analyzed under 35 ℃ simulated by intelligent artificial climate box. The results showed that the chlorophyll a，chlorophyll b，total chlorophyll content and carotenoid content of C. citratus showed a downward trend，while that of M. officinalis increased，and that of ′ Severn Sea′ increased first and then decreased. The relative conductivity，MDA content，soluble sugar and soluble protein content of C. citratus and M. officinalis were significantly increased，and SOD activity was significantly decreased. The relative electrical conductivity，MDA content and SOD activity of ′Severn Sea′ changed little. To sum up，C. citratus is more sensitive to high temperature than M. officinalis and ′Severn Sea′.

Key words: aromatic plants, high temperature treatment, physiology and biochemistry, Cymbopogon citratus, Melissa officinalis, Rosmarinus officinalis ′Severn Sea′