Quantitative evaluation of soil fertility quality of the soil under the windbreak forests alongside the Tarim Desert Highway was carried out with the IFI method (soil fertility integrated index). Results show that since the establishment of the windbreak forests,the physical structure,e.g. permeability,aeration property and water-holding capacity,of the soils bioactivity has been improving in various soil layers,and so has the soil biological activity,which is manifested mainly in higher soil microbial biomass C,N and P and enhanced activity of six enzymes,thus leading to stimulation of transformation of soil nutrients and hence differentiation of most nutrient elements between soil layers. Shelter forest soils,older in age,are higher in soil salt content,and display a phenomenon of salt accumulation in the surface soil. IFI values differ slightly between soil layers of the same soil profile,but is closely related to forest tree growth indices. In a word,the soil fertility quality of the shelter forests,drip-irrigated with salty water alongside the Tarim Desert Highway is on the way of continuous improvement.