The　thermal　hydrolysis　pretreatment　(THP)　method　was　studied　to　enhance　the　poor　biodegradability　of　waste　activated　sludge　(WAS).　THP　was　conducted　under　175℃,　0.6　to　0.8　MPa　and　maintained　for　about　30　min.　The　results　showed　48%　increase　in　volatile　solid　(VS)　disintegration　rate.　The　concentration　of　volatile　fatty　acids　(VFAs)　was　7　800　mg·L-1　on　an　average,　which　was　7　to　8　times　higher　than　that　after　pretreatment.　The　biomethanation　potential　(BMP)　of　WAS　increased　to　about　43%　by　thermal　hydrolysis.　Reactor　experiments　showed　that　combined　with　THP,　temperature-phased　anaerobic　digestion　(TPAD)　and　single-phase　mesophilic　anaerobic　digestion　(MAD)　resulted　in　0.760　and　0.719　L·(L·d)-1　in　volumetric　methane　production,　respectively,　and　0.288　L·g-1　and　0.255　L·g-1　in　methane　yield　respectively,　which　were　significantly　higher　than　that　of　conventional　MAD　treating　raw　WAS.　The　increments　were　attributable　to　more　energetic　solids　that　were　consumed　by　combined　processes.　This　could　be　indicated　by　the　48.64%　and　46.51%　VS　reduction　rate,　which　was　8%　to　11%　higher　than　the　conventional　process.　The　specific　methane　production　also　increased　50%.　Generally,　when　combined　with　THP,　the　TPAD　process　was　highly　efficient　and　the　more　practical　MAD　process　was　also　highly　efficient.　©　2016,　Science　Press.　All　right　reserved.