Acidithiobacillus　ferrooxidans　(A.　ferrooxidans)　was　applied　in　coal　biodesulfurization　and　coal＇s　pyrite　bioleaching.　The　result　showed　that　A.　ferrooxidans　had　significantly　promoted　the　biodesulfurization　of　coal　and　bioleaching　of　coal＇s　pyrite.　After　16　days　of　processing,　the　total　sulfur　removal　rate　of　coal　was　50.6%,　and　among　them　the　removal　of　pyritic　sulfur　was　up　to　69.9%.　On　the　contrary,　after　12　days　of　processing,　the　coal＇s　pyrite　bioleaching　rate　was　72.0%.　SEM　micrographs　showed　that　the　major　pyrite　forms　in　coal　were　massive　and　veinlets.　It　seems　that　the　bacteria　took　priority　to　remove　the　massive　pyrite.　The　sulfur　relative　contents　analysis　from　XANES　showed　that　the　elemental　sulfur　(28.32%)　and　jarosite　(18.99%)　were　accumulated　in　the　biotreated　residual　coal.　However,　XRD　and　XANES　spectra　of　residual　pyrite　indicated　that　the　sulfur　components　were　mainly　composed　of　pyrite　(49.34%)　and　elemental　sulfur　(50.72%)　but　no　other　sulfur　contents　were　detected.　Based　on　the　present　results,　we　speculated　that　the　pyrite　forms　in　coal　might　affect　sulfur　biooxidation　process.　©　2013　Fen-Fen　Hong　et　al.