To　improve　volatile　fatty　acids　(VFAs)　accumulation　from　hydrolysis　and　acidification　of　excess　sludge　(ES),　alkali-tolerant　bacteria　capable　of　protease-producing　were　isolated　from　ES.　A　mixed　microbial　consortium　capable　of　protease-producing　was　constructed　by　the　isolated　bacterial　strains.　The　mixed　microbial　consortium　was　inoculated　into　the　different　fermentation　periods　of　ES　to　investigate　their　effects　on　soluble　organic　compounds　and　VFAs　accumulation　from　ES　under　alkaline　conditions　(pH　10.0).　The　optimal　condition　for　VFAs　accumulation　from　ES　was　investigated.　The　results　showed　that　two　alkali-tolerant　bacterial　strains　capable　of　protease-producing　were　isolated　from　ES　and　constructed　as　a　mixed　microbial　consortium.　The　soluble　organic　compounds　concentrations　and　VFAs　accumulation　were　improved　significantly　after　the　mixed　microbial　consortium　was　inoculated　at　the　initial　fermentation,　and　the　start-up　phase　was　shortened　by　2　days.　On　the　8th　day　of　fermentation,　the　concentrations　of　soluble　protein　and　total　VFAs　reached　their　peak　values,　and　were　1.25　times　and　1.41　times　higher　as　compared　to　the　corresponding　values　from　non-inoculated　samples,　and　accounted　for　29.87%　and　44.54%　of　total　SCOD　concentration,　respectively.　Acetic　and　propionic　acids　were　the　most　prevalent　VFAs　(account　for　50.69%　and　18.19%,　respectively).　©,　2014,　Harbin　Gongye　Daxue　Xuebao/Journal　of　Harbin　Institute　of　Technology.　All　right　reserved.