The excess activated sludge was pretreated by six-methods(acid,alkaline,heat,aeration,chloroform and 2-bromoethanesulfonate(BES),respectively) in batch tests to evaluate and compare their suitability in the enrichment of hydrogen-producing bacteria.The experimental results showed that,at 35 ℃ and initial pH 7.0,the hydrogen yields of the pretreated sludge(except BES) were higher in comparison with the control test during the fermentative hydrogen production.In all tests,for fermentative hydrogen production from glucose,the sludge pretreated by acid and alkaline could obtain the maximal hydrogen production potential,using glucose as the substrate,and the hydrogen yield from glucose and specific hydrogen yield in terms of mixed liquor volatile suspend solid(MLVSS) reached 1.51 mol/mol and 27.29 mol/gMLVSS,respectively.It was concluded that the pretreatment methods led to different fermentation types.Butyric-acid type fermentation was achieved by acid and alkaline pretreatments,an ethanol-type fermentation was observed using aeration,BES pretreatments and the control,while mixed-acid type fermentation was achieved by heat and CHCl3pretreatments.