Abstract: Heat stress affects the quality and productivity of mushroom. Oxidative stress triggered by heat stress is the main reasons that lead to damage. We investigated the alleviative effects of exogenous trehalose on heat-induced oxidative stress in two Pleurotus pulmonarius strains，heat sensitive strain CCMSSC 00494 and heat tolerant strain CCMSSC 00499. The results showed that the TBARS level in heat sensitive strain was significantly higher than that in heat tolerant strain when heat stress（40 ℃）lasted 48 h，and the tolerance of heat-induced oxidative damage of heat tolerant strain was better than heat sensitive strain. Exogenous trehalose could alleviate the oxidative damage induced by heat stress by reducing the generation rate of and H₂O₂ and the activity of LOX and the content of TBARS. Additionally，exogenous trehalose had a positive effect on the activity of antioxidants SOD，and a negative effect on enzymetic antioxidants including CAT and APX，but had no effect on enzymetic antioxidants POD under the heat stress. Besides，the effect of exogenous trehalose on heat sensitive strain was more obvious than that of heat tolerant strain.

Key words: Pleurotus pulmonarius, trehalose, heat stress, heat resistance, enzymetic antioxidants