Abstract: The junior author has been collected an unusual fungus from Pishan (Guma) County in Xinjiang(Sinkiang)，on June 21，1988．This species is very closely related to Coprinus sterquilinus Fr．and Coprinus calypterotus Peck，but differs from them in the very large and subrhombiform spores 22-26×13-19μm．However，the size of spores of Coprinus sterquilinus Fr.is only 18—23×10—13μm and C．calyptratus Peck is only 17—21×10—13μm．This is the most unusual species with a whitish pileus,very finely pubescent at least over the center disc，the marginal surface area closely folded－striate before expanding，becoming broadly convex to plane and plicate-striate when maturity，the stipe equal，hollow and rather fragile,densely pubescent at base always white，not sordid，which at least for the present is being recognized as a new species. 

Key words: Coprinus giganteosporvs