p-Nonylphenol　(also　known　as　4-NP,　NP),　known　as　one　of　the　endocrine　disruptors　in　an　environment,　intensively　shows　its　estrogenic　hormones　activity.　A　quantitative　analysis　method　of　NP　isomer　mixtures　is　put　forward　in　this　essay,　which　is　suitable　to　the　analysis　of　sewage　or　recycled　wastewater　samples　that　present　a　complex　background　and　minim　NP　content.　This　method　can　be　named　as　Solid-phase　extraction-gas　chromatography-mass　spectrometry　-　multi-selected　ions　monitoring　(shortened　as　SPE-GC-MS-Sigma　SIM).　About　seventy　sewages　or　recycled-wastewater　samples　have　been　measured　based　on　the　method.　The　results　show　that　RSD　ranges　from　2.5　to　11.5　percent,　and　recovery　efficiency　ranges　from　92.2　to　98.6　percent.　The　method　can　quantitatively　determine　the　sewage　and　the　recycle　water　samples　of　contenting　NP　from　0.125　to　200　mu　g　per　litre.