Dissolved organic nitrogen is an important component of dissolved organic matter in natural aquatic system. But little is known about its characteristics. This study compared two common methods for DON analysis; persulfate oxidation(PO) and high temperature catalytic oxidation(HTCO). The results showed that both methods had their own merits,but better results were obtained using PO method. PO method resulted in higher recovery for various nitrogen-containing standard compounds(96.0 ±3.0%, excluding heteroyclic nitrogen compounds),and relative standard deviation ranged from 6.2% to 12.5% . The HTCO method yielded relatively low recovery(68.4±13.6%), and needed further impovement. This study would be helpful for the study of nitrogen biogeochemical cycling in aquatic environment.