Abstract: This paper studies on the aspect of attack,including hypha penetrating into cell wall and its distribution,and ultrastructure changes of Populus deltoides cv"Lux" by Coriolus versicolar with the aid of scanning electron microscope.The results show that white rot fungus (Coriolus versicolor) is capable of metabolixing all of the major components of wood both the carbohydrate and lignin.With this in mind,it would produce an uniform thinning or progressive removal of the wood cell wall,even in the advanced stage of white rot,little or no wood shrinkage or collapse of cells occurs and the original shape and outward appearance of the wood are maintained.These studies are of pratical significance to understand the decay mechanism of poplar,to put forward the measure of preservation and modification,and to extend the utilization of fast growing species of poplar.