Abstract: 44 isolates of ectomycorrhizal fungi comprising 38 species were cultured on MMN medium at 15 temperature gradients from 5℃ to 40℃ for 2 weeks. For growth of most isolates, the optimum temperatures ranged from 22 to 27℃ with the optima of 25℃. Most isolates stopped growing at 10℃ and 35℃. A few isolates had a poor growth at 5℃ and 40℃, but at the highest growth temperature for a long time, the isolates were much weakened, even lost their vitality at all. Most isolates of genera Boletus, Leccinum, Suillus, Xerocomus and Pisolithus were fungi of slow growing type, while those of genera Laccaria, Lactarius, Cantharellus, Lycoperdon, Gomphydius, Russula and Oudemansiella were fungi of fast growing type, and fungi of genera Amanita, Boletinus, Cortinarius, Rhizopogon, Scleroderma and Tricholomopsis grew intermediately. But [there were always many exceptions. Different isolates within a species collected from different forest sites maybe react to the temperature variation diversely. For instance, the isolates of Amanita pantherina collected from the spruce forest at altitude above 3400m grew slower than that collected from the pine forest of altitude about 2000m, but it grew faster than the later at low temperature of 10℃ for it has long been adapted to the cold alpine circumstance. They were apparently fungi of different ecotypes. From the point of view of selection of ectornycorrhizal fungi, the isolates are required to possess the fast growing ability, to have a more wide range of optimum growth temperature and to be resistant to extreme temperatures.