Abstract: The greenhouse seedlings of Anoectochilus roxburghii from 22 different provenances were used as experimental materials. Under the conditions of high temperature stress at 38 ℃ and 30 ℃ at night, and recovery at suitable temperature at 25 ℃ and 20 ℃ at night, the heat damage index, relative conductivity, chlorophyll, Pro, MDA, GSH, CAT, POD and APX were observed. The results showed that:（1） With the prolongation of high temperature stress time, the relative conductivity, Pro and MDA contents of Anoectochilus roxburghii continued to increase, while Chlorophyll and GSH contents, CAT, POD and APX enzyme activities decreased significantly, and there were obvious differences among varieties.（2） There was a very significant positive correlation between chlorophyll degradation rate and heat damage index（r=0.893）, and there was a significant positive correlation between MDA and heat injury index（r=0.835）. Therefore, chlorophyll degradation rate and MDA content could be used as reliable indexes for screening and evaluating heat resistance of Anoectochilus roxburghii.（3） Among 22 Anoectochilus roxburghii varieties, K, H, X, J, S, G, T1 and Jiangkang 1 had stronger heat resistance.