Two-stage　complete　mixing　ferment　process　was　used　for　developing　carbon　source　with　primary　sludge.　The　effects　of　hydrolysis　retention　time　(HRT)　and　sludge　retention　time　(SRT)　on　the　ferment　system　were　studied.　The　results　showed　that　the　effective　HRT　was　between　32　h　and　36　h,　and　the　effective　SRT　was　between　4　d　and　7　d.　Under　above　conditions,　the　average　effluent:　SCOD　was　in　the　range　of　980　mg/L　and　1180　mg/L,　and　supernatant　MLSS　was　in　the　range　of　50　mg/L　and　80　mg/L.　And　then,　the　separation　effect　of　the　sludge　thickener　was　clearly.　Acidogenic　bacteria　and　methanogenic　bacteria　could　be　separated　effectively　in　the　conditions.