Nitrogen (N) is generally recognized as one of the most critical nutrients to limit the river's productivity in the aquatic ecosystem. The N in sediment is released into the overlying water making the sediment N content the most important factor in determining the N concentration in the water. Thus, N release from sediments may have a significant impact on aquatic systems. Researchers have recorded the N content in sediments starting in the 1960s. The N content in the upper layers of sediments was examined from some North American lakes and from marine sediments in the North Atlantic Ocean. Scholars have developed a large body of research on the levels of N in sediments and have made considerable progress in studying N cycling and the ecological effects of N. Recent research focused mainly on total N and inorganic N, the levels of which need to be determined when studying the background N content in sediments. However, this research has not explored the biological and ecological mechanisms of N cycling in sediments. The results also show not all N in sediments may be involved in N cycling, but instead, past results indicate that only a small part of N in sediments may be involved. Therefore, it is important to investigate forms in which N exists in sediments. In this paper, we analyzed both past research on the forms of N occurring in sediments and on analytical methods used to study the N content in sediments and soils. A review of the literature revealed the methods used in N classification and measurement in sediments closely followed the N analysis methods used in soil research but lagged behind when compared with the quality of N studies in soils. For inorganic N, most studies concentrated on exchangeable N, while few considered fixed N in ammonium. Exchangeable N compounds had been extracted from sediment samples yielding a variety of extractants while using a variety of extraction techniques. Choosing the most effective method to extract exchangeable N is still controversial. No systematic research has looked at the influence of extraction methods on the analysis of exchangeable N in sediments. The debated continues on whether to use fresh wet sediment or dried sediment in measuring the exchangeable N or other fractions of inorganic N. The effect of dissolved N on measuring exchangeable N is also uncertain. To determine N bioavailability in sediments, some domestic scholars employed the sequential extraction method used in the studies of marine sediments and lake sediments and N was divided into four fractions: ion-exchangeable forms, carbonate forms, iron-manganese oxide forms and organic matter-sulfide forms. The sequential extraction method provides new insights into the future study of N content in sediments. Although investigating the fractions of organic N in sediments is important, the measurement method used to measure organic N primarily has depended on the researchers’ experience with the method, and no reliable method exists to determine organic N content in sediments.