In order to determine the characteristics of nitrate pollution found in loose rock pore water in the source of the Hutuo River and its migration process, eight groundwater sampling points in Fanshi County were selected and analyzed，and the results are as follows: The content of constant element Ca2+ in the groundwater is significantly larger than that of Na+, and there is a significant negative correlation between them. There is a significant positive correlation of the content between Na+ and Cl-. Along the groundwater flow, the HCO-3content, which is the main anion component, tends to decrease, but the relative amplitude is small.The Cl-content increases with the increase of groundwater flow, and the relative variation is large. Basically, the dynamic of groundwater is mainly characterized by infiltration-runoff, with infiltration-runoff-evaporation as supplement, and the chemical reaction of groundwater is dominated by leaching and filtration mixed with concentration action. The nitrate-nitrogen pollution of groundwater in the source of Hutuo River is serious.The content of the NO-3 from the sampling points is from 3.6 to 28.7 mg/L , with an average value of 14.3 mg/L and exceeding rate of 75%, and all the samples below Haojiawan exceeded the standard； With the increase of nitrate content, δ15N shows no obvious decreasing trend , and the sampling of δ15N/δ18O doesn' t form the proportional formula 2∶1. Combined with active alternation of surface water and groundwater environment, it can be inferred that there is basically no denitrification in the study area； Traceability analysis of δ15N, δ18O shows that 12.5% of the samples are polluted by the domestic sewage and livestock excrement , 87.5% of the samples are polluted by soil, domestic sewage, livestock excrement , chemical fertilizer and rainfall, and the corresponding contribution rates are 62%, 22%, 16% respectively. It also shows that the mineralization and nitrification of organic matter are taking place in this area.