The influence of medium variety、thermal treatment of the soil samples and inhibitor to the isolation effect of actinomycetes was studied by plate paint isolation methods.The results showed that: ①The isolation results of gauze No.1(GA) and straw decay substance agar(SDSA) might reflect basic station of soil actinomycetes. ②Thermal treatment (120℃?1.0h)in soils might promote actinomycetes spore sprouting and increase the quantity and variety of actinomycetes. The quantity and varieties of actinomycetes in the Soils that were treated with 120℃?1.0h were increased by 5.5%～54.9% and 12.5%～100% than the check of none-thermal treatment respectively. But thermal treatment had no effect on reduce the quantity of bacteria. ③The quantity of bacteria had significant reduction by adding 75?g/mL K 2Cr 2O 7 and 1～3?g/mL penicillin at same time to the isolation medium, and had little effect on the quantity and varieties of actinomycetes. Actinomycetes quantity (?10 6cfu/g) and variety of the treating of 75?g/mL K 2Cr 2O 7 and 1～3?g/mL penicillin in No.1 soil on SDSA medium had reductions by 0～58.8% and 0～18.2% compared with treating of 75?g/mL K 2Cr 2O 7, respectively. ④streptomycin might not been used for bacterteria inhabitor in the isolation of actinomycetes.