In Northwest China

the climate is mainly arid and semiarid and loess is widely distributed. This paper firstly presents the climate characteristics of three representative cities in Northwest China for nearly 50 years and the water storage capacities of the three types of loess. The water balance method proposed by Chen，Khire et al is used to evaluate the feasibility of using loess as soil cover material

and then the design thickness of monolithic loess soil cover is determined. The analyses demonstrate that: in Northwest China

hot rainy and the lush vegetation in summer compared with cold dry and the withered vegetation in winter

the intensities of precipitation and evapotranspiration have good synchronization

which is just application for soil cover. When the loess is used as soil cover material in the Northwest China

the design thickness of monolithic soil cover ranges from 0.54 to 1.92 m. The design thickness depends on the climate condition and the type of loess. From arid

semiarid to semihumid regions

the thickness becomes larger. For a given region

the design thickness for the silty loess is the least

and that for the sandy loess is the largest. The use of loess as soil cover material for landfills in Northwest China has advantages with respect to both technical and economical aspects. It is deserved to put the technique into engineering practice and call for more research.