Seasonally　variation　of　water　salinity　is　observed　worldwide,　the　mechanisms　of　water　salinity　are　not　well　understood　due　to　natural　factors　and　anthropogenic　activities.　Quantification　water　salinity　source　are　challenging　since　complex　influence　factors,　especially　in　agricultural　regions　irrigated　with　multi-water　sources.　In　the　lowland　area　of　North　China　Plain,　transferred　water,　brackish　shallow　groundwater　and　fresh　deep　groundwater　were　combinative　utilized　to　relieve　prominent　contradictions　between　regional　water　shortages　and　grain　production.　In　this　study,　influence　factors　of　surface　water　(canal　water,　pond　water)　and　shallow　groundwater　salinity　were　identified　and　quantified　through　statistical　analysis,　deuterium　excess,　and　ionic　relationship.　Salinity　of　canal　water　and　pond　water　increased　in　dry　season　and　decreased　in　rainy　season,　while　salinity　of　shallow　groundwater　decreased　in　dry　season　after　water　transfer　and　rainy　season,　but　increased　in　dry　season.　Evaporation　and　mineral　dissolution　were　main　factors　for　surface　water　salinity　in　dry　season,　with　mineral　dissolution　was　the　more　important　one.　The　contribution　ratio　of　evaporation　and　mineral　dissolution　for　canal　salinity　were　4.4　and　49.1%　in　dry　season　after　water　transfer,　7.1　and　34.4%　in　dry　season,　and　that　for　pond　water　salinity　were　12.4　and　18.3%　in　dry　season,　respectively.　Precipitation　and　surface　runoff　were　main　factors　for　surface　water　salinity　in　rainy　season.　The　contribution　of　surface　runoff　for　canal　water　and　pond　water　salinity　were　66.1　and　45.8%,　respectively.　Salinity　of　canal　water　and　shallow　groundwater　was　temporary　decreased　by　water　transfer.　Domestic　sewage　from　rural　areas　had　larger　influence　than　agricultural　activities　for　salinity　increase　of　pond　water　and　shallow　groundwater.　Mineral　dissolution　was　the　main　contributor　for　shallow　groundwater　salinity,　with　contribution　ratio　larger　than　60%　in　different　periods.　This　study　demonstrated　and　quantified　salinity　source　of　surface　water　and　shallow　groundwater　and　may　deepen　our　understanding　of　water　management　under　multi-water　resources　utilization.　©　2021　John　Wiley　&　Sons　Ltd