Abstract: For observing the transfer cells in epiderm of the roots by optical microscope,the method is taken as follow:after the leguminous plants Albizia julibrissin,Astragalus sinicus,Medicago sativa induced by Rhizobia,their root segments where root hair grows densely and swells a little are selected to be fixed in FAA.Through a series of treatment such as being embedded in GMA,semithin sections(3 μm),staining with PAS reaction,the root cross sections were observed by optical microscope under the oil objective.The result shows that on the tangential exowall of the epidermal cells or exodermis of the roots,the wall ingrowth is easy to be found.It is the typical epidermal transfer cells of root.This method is not only simple with a low cost but also easy to determine the position of the transfer cells in the root.