FT-ICR-MS　technology　and　analytical　methods　were　used　to　comprehensively　characterize　the　compositional　and　structural　characteristics　of　DOM　molecules　in　the　overlying　water　of　the　Beiyun　River,　revealing　the　migration　and　transformation　rules　of　DOM　molecular　composition　and　evaluating　the　potential　environmental　impact　of　DOM　molecular　composition.　The　results　indicated　that　the　DOM　molecular　compounds　in　the　overlying　water　of　the　Beiyun　River　were　mainly　composed　of　lignin　(63.19%)　and　proteins　(12.96%).　The　stable　DOM　molecular　formulas　in　the　overlying　water　were　mainly　refractory　lignin　and　basic　metabolites　and　secretions　that　are　continuously　recycled　and　regenerated.　The　diversity　of　unique　DOM　molecular　formulas　correlated　with　intensity　anthropogenic　activities.　The　common　DOM　molecular　formula　that　was　preferentially　transformed　or　degraded　was　mainly　lignin　with　highly　chemically　active　carboxyl　and　hydroxyl　groups　and　liable　lipids,　proteins　and　carbohydrates.　The　Beiyun　River　had　the　characteristics　of　high　input　of　exogenous　wastewater,　resulting　in　a　large　amount　of　liable　DOM　compounds　in　the　overlying　water,　which　increased　the　potential　risk　of　river　eutrophication.　©　2022　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.