The Yellow River flows through nine provinces and regions of China，providing abundant water resources for the living，production and agricultural irrigation of urban residents along the way.In a water supply project of a city in Ningxia，which diverts water from the Yellow River，nitrate nitrogen is one of the important detection parameters.In order to analyze nitrate nitrogen in water more accurately，three commonly used detection methods，namely ultraviolet spectrophotometry，ion chromatography and continuous flow analysis，were compared in this paper.The results show that the correlation coefficient，precision and accuracy of the standard curves of the three methods can meet the quality control requirements of water environment monitoring standards.Continuous flow analysis method has the advantages of high automation，fast speed and accurate results.The results can provide reference for the detection personnel to choose the appropriate detection method.