Green　tea　has　distinct　astringency,　bitter　taste,　and　typical　green　flavor　because　of　its　post-harvest　treatment　without　withering　and　enzymatic　oxidation.　Microbial　fermentation　has　been　identified　as　a　promising　strategy　that　could　give　green　tea　infusion　a　special　taste　flavor.　This　might　be　linked　to　the　metabolic　transformation　ability　of　microorganisms.　In　this　study,　starter　culture　of　edible　mushroom　Pleurotus　sajor-caju　(oyster　mushroom)　was　used　for　submerged　fermentation　of　green　tea　infusion　in　order　to　improve　its　flavor　and　taste　quality.　The　volatile　profile　determined　by　headspace　solid-phase　microextraction,　coupled　with　gas　chromatography　mass　spectrometry,　showed　that　the　contents　of　(Z)-2-penten-1-ol　and　methyl　heptadienone　in　green　tea　infusion　were　decreased　significantly　by　the　fermentation　with　the　basidiomycete　P.　sajor-caju　(p　＜　0.01),　which　would　alleviate　the　herbal　and　grass　flavor　of　green　tea　infusion　to　a　certain　extent.　Meanwhile,　the　contents　of　linalool　and　geraniol　were　increased　9.3　and　11.3　times,　respectively,　whereas　methyl　salicylate　was　newly　produced　after　fermentation　by　P.　sajor-caju,　endowing　the　fermented　tea　infusion　with　a　pleasant　flower　and　fruit　aroma.　In　addition,　the　polyphenol　profile　was　determined　using　high-performance　liquid　chromatography　equipped　with　ion　trap　mass　spectrometry,　and　the　results　indicated　that　the　contents　of　most　polyphenols　in　green　tea　infusion　decreased　significantly　after　fermentation　by　P.　sajor-caju.　The　reduction　of　catechins　and　anthocyanins　in　fermented　green　tea　infusion　alleviated　the　astringency　and　bitterness.　Moreover,　the　antioxidant　activity　of　fermented　green　tea　infusion　was　obviously　decreased,　especially　the　DPPH-free　radical-scavenging　ability　and　the　ferric-reducing　power.　However,　it　is　noteworthy　that　the　ABTS-free　radical　scavenging　ability　was　improved　compared　with　the　unfermented　one,　indicating　that　the　increased　tea　pigments　and　volatile　metabolites　(such　as　linalool　and　geraniol)　after　fermentation　with　P.　sajor-caju　may　also　contribute　to　the　antioxidant　capacity　of　fermented　green　tea　infusion.　Overall,　the　innovative　approach　driven　by　P.　sajor-caju　fermentation　has　achieved　promising　potential　to　manipulate　the　green　tea　flavor.