Human can be exposured to arsenic (As) through the air, drinking water and food and so on. In this paper, the total As concentration of 69 hair samples of local residents living in Hequ (HQ), Shizuishan (SZS), Zhongwei (ZW) and Linxia (LX) and 4 filtered water samples of Yellow River were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Differences of hair arsenic levels in different gender and age groups and the correlations of As level between hair and water were studied. Hair samples were pretreated by microwave digestion with a satisfactory result. The recoveries and RSD of the method were 90.1%～101.9% and 2.9%～4.2%, respectively. The results showed that hair As concentration ranged for 0.01～1.73 μg·g-1 with an average of 0.33 μg·g-1, followed the sequence of ZW>HQ>LX>SZS. Kruskal Wallis test showed statistical difference (p=0.010) among concentrations of As in hair from the different sampling sites, this indicated that the living area had an effect on the content of As in the residents’ hair. There was no significant difference observed among different gender (p=0.158) and age (p=0.159) groups, but relatively high level of As concentration in hair for males was observed, while the mean concentrations of different age groups showed an age-dependent decrease. Compared with the literatures, the As concentration level of hair in this study was higher than that in most areas, but obviously lower than that in the arsenic-endemic region. The As level in the water of the Yellow River ranged for 2.31～10.41 μg·L-1, which was higher than that of the lower reaches of the Yellow River, but didn’t exceed the surface water environmental quality standard. Pearson correlation coefficients showed that As concentrations in water samples had correlations with Pb, Cu, Cr and Cd and had significant positive correlation with As concentrations in hair samples. In conclusion, the residents living near the sampling sites were at relatively high risk of As exposure, which may mainly derive from industrial and agricultural emissions. This paper could provide experimental data and theoretical basis for As pollution in northwest region such as Gan-Ning-Meng area of China.