In　order　to　study　the　source　of　nitrate　in　surface　water　and　groundwater　near　a　domestic　sewage　discharge　river　in　the　Baiyangdian　watershed,　including　the　Fuhe　River　and　Baiyangdian　Lake,　shallow　groundwater　and　deep　groundwater　samples　were　collected　in　July　2014.Water　chemistry　and　stable　isotopes　(δ2H　and　δ18O)　were　used　to　study　the　relationship　between　the　surface　water　and　groundwater.　δ15N　was　used　to　explore　the　source　of　nitrate.　The　results　show　that　urban　and　rural　domestic　sewage　discharge　to　Fuhe　River　and　then　experience　evaporation.　Shallow　groundwater　is　affected　by　the　Fuhe　River,　Baiyangdian　Lake,　and　lateral　recharge　from　groundwater　in　the　Taihang　Mountain　area.　There　are　16.7%　of　shallow　groundwater　samples　exceeds　the　NO3-　threshold　for　drinking　water　according　to　the　World　Health　Organization　standard.　Due　to　the　effect　of　self-purification　capacity,　the　NO3-　mass　concentration　in　the　Fuhe　River　is　higher　in　the　upstream　area　than　in　the　downstream　area.　Due　the　regional　water　flow　from　northwest　to　southeast,　the　NO3-　mass　concentration　in　the　shallow　groundwater　is　higher　in　the　south　bank　area　than　in　north　bank　area.　The　shallow　groundwater　near　the　Fuhe　River　and　Baiyangdian　Lake　is　recharged　by　surface　water.　In　addition,　soil,　fertilizer,　and　point　sources　are　also　major　sources　for　groundwater　nitrate.　Urban　and　rural　residential　living　and　agricultural　production　activities　are　the　main　reasons　for　surface　water　and　groundwater　nitrate.　©　2018,　Science　Press.　All　right　reserved.