Over the last several decades, significant reductions in the concentrations of stratospheric ozone (O₃) have been reported. The reduced ozone concentration causes an increase in the UV-B radiation that reaches the earth's surface; this is one of the most important environment problems worldwide. Although UV-B radiation accounts for only about 1.5% of total solar radiation, it is readily absorbed by biomacromolecules, with the result that increased UV-B radiation inhibits the growth of most plants. Biological soil crusts (BSCs) are complex assemblages of minute organisms that are formed primarily by cyanobacteria, green algae, lichens, and mosses on the surface of soil. Previous studies have shown that increased UV-B radiation has detrimental effects on BSCs. However, we observed that they can recover from UV-B stress, and still flourish in desert regions. Moss crust has great ecological significance in desert areas, where it is the dominant component of BSCs, and a major pioneer species in community succession processes. In desert ecosystems, plant life is damaged as a result of adverse environmental conditions, such as strong light, extreme temperature, salinity, and water deficit. Several studies have examined the effects of environmental factors on the species composition and physiological properties of BSCs. However, fewer studies have addressed the recovery mechanisms of BSCs after they are subjected to environmental stresses. We used UV-B radiation (2.75, 3.08, 3.25 and 3.41 W/m²) to simulate the depletion of 0% (control), 6%, 9% and 12% of stratospheric ozone at the latitude of Shapotou region and recovery after a return to visible-light conditions (150 μmol m^-2 s^-1) and evaluated the effects of this exposure on physiological variables and cell ultrastructure in the moss Bryum argenteum, which we isolated from BSCs in the Tengger Desert in northern China. The results indicated that the photosynthetic pigments content, flavonoid content, and antioxidant enzyme activity in B. argenteum decreased, while malondialdehyde (MDA) content increased after exposure to UV-B radiation. The ultrastructure of the chloroplasts of B. argenteum subjected to enhanced UV-B was significantly disrupted, as follows: the chloroplast structure was distorted, the arrangement of the thylakoids in the chloroplast was disordered, expanded or even obscured, and the number of osmiophilic granules increased. The degree of damage increased with increasing UV-B radiation. However, visible light could partially repair damage induced by enhanced UV-B radiation. The aim of the present study was to discuss the responses of B. argenteum to UV-B radiation and its repair capabilities, and to improve the understanding of the mechanisms of the tolerance of B. argenteum to UV-B radiation.