Red maple( Acer rubrum L.),originated in North America,is one of the Aceraceae cultivated species. Red maple has high ornamental value for its beautiful treelike and gorgeous leaf color. Recently,many scholars have done researches about it in order to make more widespread in China. However,those studies are limited to breeding cultivation technology and color change mechanisms of leaves,while the studies of red maple's physical response mechanisms to high temperature have not been reported. High temperature will affect the physiological growth of plants,and it may also influence colorful-leaf plants' leaf color expression. While most cities in southern China get high temperature in summer,the climate has largely limited the introduction of the red maple. In order to explore physiological adaptive mechanisms of the red maple to adverse environments,continuous high temperature and drought stress was applied to three kinds of red maple( Acer rubrum L.) seedlings,including October Glory,Jeffersred and Brandywine. Measurements included contents of osmoregulation substance,activity of protective enzyme,cell membrane permeability,and malonaldehyde( MDA) content and relative amount of chlorophyll in the plant leaves and seedlings morphological characters. The results showed that aftertwo days of the treatment,chlorophyll and soluble protein contents,and superoxide dismutase( SOD),peroxide enzyme( POD) and catalase enzyme( CAT) activities of plant leaves significantly decreased respectively,and the leaves of October Glory and Jeffersred began to be damaged,while those of Brandywine were still in good condition. After four to six days,there were significant changes in the physiological indices of the three species except for the contents of soluble protein. In the meantime,the contents of proline( Pro) and conductivity were keeping increasing while the contents of MDA showed a decline tendency,indicating that the plant biological controlling mechanisms began to function. Later,all the leaves of Jeffersred turned to yellow,and the injury index of the rest two species was approximate 70% respectively. The contents of MDA and Pro,and conductivity were at maximum and all the leaves in the three species died ten days after the treatment began. The results indicated that the resistances to continuous high temperature of the three species used in the experiment were different. According to a comprehensive evaluation based on subordinate function of fuzzy mathematics,Brandywine was the best among the three species in heat-resistance,compared with a lower heat-resistance in October Glory,and the lowest resistance in Jeffersred. This result is consistent with injury index.