Abstract: Nitrate content is an important index to evaluate the quality of groundwater which affects human health directly. As to evaluate the nitrate contamination in groundwater in Tianjin, an investigation and watersampling analysis on nitrate concentration in Tianjin groundwater was performed in 2011, and the nitrate pollution status was studied. The results showed that: the average concentration of NO₃--N in groundwater was 7.11 mg/L, and about 12.06% samples exceeded the criterion of national drinking water quality. The nitrate concentration of groundwater was affected obviously by sampling period, sampling area and sampling depth. The nitrate concentration in groundwater after raining period (6.89 mg/L) was lower than that before raining period (7.33 mg/L). The nitrate concentrations in groundwater of 0-30 m, 30-100 m and≥100 m depth were 47.66 mg/L, 13.5 mg/L and 0.18 mg/L respectively. As being affected by cultivation system, fertilizer application and landform, there were obvious differences between the nitrate concentrations of different areas. The nitrate concentrations of Xiqing and Jixian were exceeded 10 mg/L, higher than other districts; the nitrate concentrations of Wuqing, Baodi and Jinghai were between 6.95 mg/L and 9.82 mg/L. The nitrate concentrations of other 5 districts were under 5 mg/L.