In　this　study,　the　transformation　mechanism　for　the　sulfur　element　during　pyrolysis　of　sewage　sludge　(SS)　was　investigated.　The　amount　of　H2S,　which　was　mainly　produced　from　methionine　pyrolysis　at　low　temperatures,　increased　stepwise　with　increasing　temperature　in　the　range　of　400-600　°C.　The　pyrolysis-gas　chromatography-mass　spectrometry　(Py-GC-MS)　results　showed　that　a　large　amount　of　sulfur-containing　heterocyclic　compounds　was　found　in　the　tar　from　sulfur-containing　amino　acids.　The　electrospray　ionization　Fourier　transform　ion　cyclotron　resonance　(ESI　FT-ICR)　MS　results　further　confirmed　that　the　sulfur　element　in　sulfur-containing　amino　acids　was　mainly　transferred　into　the　tar　phase.　Polymerization　was　the　main　reaction　during　the　low-temperature　pyrolysis　of　sulfur-containing　amino　acids.　In　addition,　methylation,　deamination,　desulphurization,　and　decarboxylation　also　took　place　during　the　pyrolysis.　X-ray　photoelectron　spectroscopy　(XPS)　results　indicated　that　the　content　of　sulfur-containing　inorganic　compounds　was　very　low　in　char.　With　an　increase　of　pyrolysis　temperatures,　the　heterocyclic　compounds　further　cracked　to　form　H2S.　The　above　results　indicated　that　H2S　mainly　came　from　methionine　during　the　pyrolysis　of　SS　at　low　temperatures.　A　potential　mechanism　for　the　transformation　of　the　sulfur　element　during　the　pyrolysis　of　SS　was　proposed.　©　2020　American　Chemical　Society.