Abstract: The contaminated artificial bed-logs of Lentinus edodes found in Pingquan, Hebei Province were used as the test materials, the method of tissue isolation combined with morphological characteristics and multiple gene sequences analysis were used.The biological characteristics of contaminating bacteria and its interaction with the hyphae of four L.edodes strains widely planted in production were further studied, in order to provide reference basis for the control of contaminated artificial bed-logs of Lentinus edodes caused by P.variotii.The results showed that the contaminated bacterium was identified as Paecilomyces variotii,P.variotii was thermophilic, and the lethal temperature was as high as 89 ℃.The optimum conditions for the growth of its hyphae were as follows, temperature 35 ℃,pH 6,glucose as carbon source and ammonium chloride as nitrogen source.Light promoted the hyphae growth of P.variotii to a certain extent.Paecilomyces variotii showed varied polluting capacity to the artificial bed-logs from different strains of L.edodes.It could inhibit the hyphae growth of L.edodes by producing secondary metabolites, competing space and nutrients.It was necessary to strictly control the temperature conditions, strengthen ventilation and environmental sanitation management in the process of production, which was helpful to prevent the occurrence and harm of P.variotii.This was the first report of P.variotii contaminated the artificial bed-logs on the cultivation of L.edodes.