Rhododendrons ( Rhododendron ) are ornamental plants that exhibit poor thermotolerance. To provide a theoretical basis forthe production and application of Rhododendron in summer, effects of high temperature and low light stress on the growth,physiological characteristics (including photosynthesis), and leaf structure of Rhododendron were explored. Two Rhododendroncultivars, Rh. ‘Fen Zhenzhu’ and Rh. ‘Zhuangyuan Hong’, were selected. Rhododendron plants were subjected tostress in 6-day intervals in an artifi cial climate box with 37.5, 75, 112.5, and 150 μmol m −2 s −1 photosynthetic photon fl uxat 38 °C. The leaf anatomical parameters and physiological indexes, including gas exchange parameters, relative water content,relative conductivity, chlorophyll and osmotic substance contents, malondialdehyde and hydrogen peroxide levels, andenzyme activity, of Rhododendron under high temperature and diff erent low light levels were measured. The results showedthat the combined stressors of high temperature and low light caused damage to leaves, such as loss of water, cell membranedamage, decreased net photosynthetic rate, and changes in leaf structure. Additionally, with the decreased light intensitycaused more damage, and diff erent damage mechanisms were found in diff erent cultivars and treatments.