Abstract: The present paper expounds the ecological characters and distribution of Nostoc flagelliforme in Siziwangqi county, Inner Mongolia. In this region, the abundance of N. flagelliforme increases from south to north according to the diminution of annual precipitations. In the South and midst parts the steppe and desert steppe region, the distribution of N. flagelliforme is scattered. In the small half-shrub desert region where the dominant species are Salsola passerina and Reaumuria soongorica, the distribution of N. flagelliforme is concentrative and associated with special types of communities. N. flagelliforme seems to be capable of adapting to drought environment conditions and some of its ecological characters can be summed up as follows: resistantance to drought, high temperature, salinity, alkalinity and soil impoverishment and effective adaptation to low light intensity and resistlessness to moisture, the soil rich in calcium is essential to the growth and distribution of N. flagelliforme. Some suggestions for the preservation, exploitation and utilization of this wild .resources are also offered.