In order to provide references to the development and practical utilizations of the lichen symbiotic alga, we isolated two photobionts by using lichen species Peltigera rufescens and Peltigera elisabethae as the main research objects and studied the morphological characters, rDNAITS sequences as well as the capacities of the photobionts in the formation of the microbiotic soil crust under the laboratory artificial conditions in this research. (1) The I₁b and L₂ photobionts which were isolated from P. elisabethae and P. rufescens respectively belong to cyanobacteria. According to the analysis of phylogenetic tree which was constructed based on ITS sequences, I₁b was identified as Microcoleus vaginatus with 100% bootstrap value, while culture L₂ was identified as Nostoc sp. with 93% bootstrap value. (2) The most suited conditions for the microbiotic soil crust formation under laboratory artificial desert extreme situation were that 10% of water moisture content, 3∶1 (M. vaginatus: Nostoc sp.) ratio and 10 μg/cm² inoculation amount of photobionts.