Abstract: Through culture, dissection and microobservation, the biological characteristic of Agrocybe cylindracea strain L1 was studied. As a result, it is a quality train. Its fructifications were enlarged and the flesh of fruit bodies were thicken. The fructification mean weight was 28.77 g.The fructifications hyphal system of Agrocybe cylindracea strain L1 was monomitic.It was also showed that the hapha of different fructifications position and vegetative hypha were all achromatic color, transparent and with branches, tabulas, lock connections but their diameter and the arrangement way were different apparently. The diameter of  stipe hapha was at the most and the diameter of substrate hapha diameter was least. The haphas of stipe and the medulla were parallel and the haphas of veil were intertexture.