Abstract: The methods of three-dimensional fluorescence spectroscopy and Pearson correlation analysis were applied to determine the pollution characteristics and origins of DOM in a typical urbanized river, Baitabu River in northeastern China. The results indicated that fluorescence peak types of the river included UV fulvic-like peak (A peak), visible fulvic-like peak (C peak), protein-like peak (B peak) and protein-like peak (T peak). The major components order of DOM was protein-like>soluble microbial byproduct-like>fulvic-like>humic-like. The relative content of spatial distribution of DOM showed middle and lower reaches>upper reaches. The source of DOM in Baitabu River showed double characteristics of land-sourced materials and microbial degradation, and the internal pollution caused by microbial degradation could not be ignored. According to Pearson correlation analysis, the DOM concentration was correlation with NH₃-N and TP concentration which showed a significant positive relationship, but was significantly negative correlation with dissolved oxygen concentration.