Abstract: The free-disinfection isolation method of Armillaria mellea complexes was modified in 4 ways.Firstly,the tissues of trees which were well parasitized by A.mellea complexes should be selected as the materials for culturing rizhomorph,but the tissues of grasses(or bamboo),or the soil that A.mellea complexes existed are not suitable.Secondly,the target tissues were cultured in a high humidity and temperature of 15℃,then well-grown A.mellea complexes rhizomorph can be obtained.Thirdly,the culture medium,made up of maize∶soya∶sucrose∶water=6∶1∶1∶26 in mass,not only can supply enough nutrition,but also can hinder the growth of the bacteria and other fungi,which was a concomitance of A.mellea complexes rhizomorph.And last,if the rhizomorph for isolation was exposed in the air for 8-10 minutes,then the infected probability by bacteria can be reduced significantly.