In　order　to　discuss　the　nonylphenol　(NP)　biodegradability　effect　in　the　wastewater　treatment　process,　the　primary　metabolites　and　route　of　NP　had　been　analyzed　in　the　molecular　level　by　the　interpretation　of　gas　chromatography　mass　spectrometry　(GC-MS)　and　the　two　experimental　methods.　A　method　was　that　activated　sludge　degraded　two　types　of　simulating　sewage　comparatively.　Type-1　wastewater　was　made　up　of　water,　glucose,　peptone　and　inorganic　salts,　and　type-2　sewage　was　mixed　up　of　NP　and　type-1　as　comparison　wastewater.　The　other　experiment　was　that　dominant　bacteria　group　metabolized　the　culture　medium　contained　NP　as　only　organic　carbon　source.　The　results　show　that　the　NP　primary　metabolites　from　the　activated　sludge　experiments　are　a　series　of　short　chain　alkyl　phenols　with　butyl,　amyl　or　hexyls.　There　are　different　methyl　branch　structures　correlated　with　isomerous　nonyl　of　NP　in　the　alkyls.　The　primary　metabolites　from　the　dominant　bacteria　experiment　have　alkyl　phenols　and　benzene　acetic.　The　bio-degradation　pathways　of　NP　would　be　that　the　long　branches　in　nonyl　of　NP　are　firstly　degraded　into　short　methyl　branches,　which　come　into　being　a　series　of　short　chain　alkyl　phenols　with　different　branch　structures.　The　middle　products　should　be　further　metabolized　into　simpler　compounds,　such　as　benzene　acetic.　Based　on　the　endocrine　disrupter　characteristic　of　alkyl　phenol　compounds,　the　short　chain　alkyl　phenol　compounds　still　have　estrogen　hormone　effect,　and　their　environmental　effect　must　be　pay　attention　in　the　pollutant　control　of　NP.