Abstract: This paper studied the dynamics of microbial communities in degraded soils of central Tibet under straw amendment and its effect on soil fertility.The results showed that straw amendment,and soil covering with spring highland barley (Hordeum vulgare var.nudum) straw in particular,could supply a beneficial soil environment for the relatively balanced growth of soil microbes,e.g,reduced water evaporation,appropriate temperature,and increased content of organic matter and nutrients.All the results demonstrated the possibility of straw amendment in recovering soil fertility and in reconstructing of soil structure in a relatively short period.