Abstract: Chloride and nitrate，as a conservative and a semi-conservative ion，have been used to examine the recharge history, reconstruct the related climate change and vegetation transitions and so on in the cold-arid desert region of northwest China. In general，they always transport with rainfall in the soil，even though the nitrate always takes part in plenty of bio-chemical reactions. And soils are crucial to the functioning of the Earth system, since they are at the interface between the atmosphere，lithosphere，hydrosphere and biosphere，and influence terrestrial net primary production, climate regulation, and water quality. So revealing the spatial distribution of the dissolved chloride and nitrate is favor to prohibit the potential water contamination caused by nitrate leaching from upwards, and to understand the impacts on the desert ecosystem. The water content and nitrate and chloride concentrations with the NO3-/Cl- were measured in different profiles and different soil types in verticality. It was found that the distributions of Cl-、NO3- tend to be piston oscillations as a result of the severe evapotranspiration. The average concentrations of Cl- increase from 35 mg/L to 6 545 mg/L，with the maximum rising from 41 mg/L to 9 592 mg/L，correspondingly. Meanwhile，the average concentrations of NO3- range from 8 mg/L to 1 227 mg/L，and the average NO3-/Cl- molar ratios are between 0.03 and 1.75. The relatively higher NO3- concentration in Wuwei and Minqin areas，especially in the profiles WW1、WW3、MQ1, may demonstrate the effects of the anthropogenic inputs. And the declines of the NO3-/Cl- molar ratios from east to west may be due to the decrease of the rainfall from southeast to northwest in the area. Plant’s taking-up of moisture and nitrate preferentially makes the nitrate distribute differently in vadose zone. The presence of peaks in the nitrate profiles is probably proportional to the preferential taking-up of nitrate and due to be coincidence with the nutrient profile，which leads the concentration of nitrate to decline sharply with the soil depth. The near surface peaks in NO3- with higher NO3-/Cl- molar ratios reflect active modern N-fixation by cyanobacteria. The higher NO3-/Cl- molar ratios are consistent with the bulge shaped Cl-，which probably indicates that relatively less vegetation coverage in the drought environment plays a limiting role in the uptake of nitrate. The characteristics of chloride and nitrate tend to be distinct in different soil types .The piston distribution of chloride and nitrate in the sand soil，which has a great conductivity and inferior water binding capacity, attributes to the plant taking in the nitrate within its cycling in the soil along with intensive evapotranspiration，while the concentration of chloride and nitrate in the clay soil decreases with the moisture content.

Key words: desert areas； , chloride； , nitrate； , NO3-/ Cl- molar ratios； , soil moisture