Totally 2135 transformants were generated after transforming the nematode- trapping fungus Arthrobotrys oligopsora with plasmid pBChygro. Among these transformants, one (YMF1.00110) losing the ability to form trapping-device was screened. This transformant grows slowly and shows different morphologies as compared with the wild type. The results of Southern blot analysis indicated the transfromant had single copy integrations of pBChygro. Furthermore, the integration pattern and tagged efficiency of parts of transformants also were presented in this paper.