Abstract: The fine structure and development of desert algae crusts were studied in Shapotou, Zhongwei county, Minxia Hul autonomous region(37?7', N 104?7', E),where an experimental station with pilots were enclosed and planted respectively in 1956, 1964, 1981 and 1994.The community structure and spatial distribution of algae on micron degree were firstly illustrated by using light microscope, SEM and polarizing microscope.The structure characteristics of the crusts and the eco-physiological behavior of dominant algae were analyzed in terms of algal biomass, physical and chemical propenies and mineral composition in vivo.The relationship between the developmental degree of the crust, the community structure, soil micromorphology and the degree of mother material mineralization were determined biologically, agrologically and mineralogically.It is indicated that the use of terrestrial algae is feasible in desert fixation and soil amelioration.