Biomass measuring techniques of soil algae have long been not uniform and have serious practical errors in each. This has severely retarded the research development of this region. In this study, we collected desert algal crusts of different developmental stages (42, 34, 17, 8, 4 aged) and topsoil of unconsolidated sand located in Shapotou, Zhongwei County, in Ningxia Autonomous Region. We conducted direct counts by using acridine orange and 4,6-diamidino-2-phenylindole dyes under fluorescence microscope; d...