Loess forms from dust being deposited over the millennia under varied climatic conditions in the Loess Plateau of China through climate evolution.Influenced by monsoon,rainfall,temperature,dust characteristics,and so on.By forming under different regional climatic conditions,loess exhibits a wide range of microstructural morphologies.From its microscopic structure,we can obtain datum on particle size distribution,pore size distribution,and cementing quality,which can more fully elucidate the formation of regional loess.Because the microstructural characteristics of loess are directly related to dynamic deformation,strength,and arrangement mode,the features of loess microstructural formation types and regional deposition by particle size can be studied by an intuitive method in seismic hazard analysis.In contrast,in similar Midwestern shallow eolian loess soils(not considering landform),analysis of the microstructure under different soil environments is by sediment size.Western loess-forming microstructures are divided into five categories:(1)near a sand source,formed by fast sand dropping;(2)weakly formed by strong sand dropping;(3)formed in cold weather by slow sand dropping;(4)weakly formed in warm,damp weather;and(5)strongly formed in warm,damp weather.Differences in particle size,particle size distribution,particles between,degree of consolidation,contact,and so on,determine the microstructure types in the sediments,which have important effects on engineering properties.By analyzing the formation mechanism of loess by study of the microstructure in regional climates,and then further by analyzing the loess area,the regional differences in soil microstructure can determine the sediment deformation(either strong or weak).Such information is useful in building engineering site design and in determining corresponding protective measures.