Abstract: In order to improve the sludge fermentation performance and increase the short chain fatty acid(SCFAs) production,the influence of different basicity(alkaline pH=10,super-alkaline pH=12 and super-alkali pretreatment pH=12 alkaline pH=10) on WAS hydrolysis acidification was studied at25℃.The results showed that the super-alkaline fermentation and super-alkali pretreatment-alkali fermentation could improve the production of SCOD,DNA,protein and polysaccharide compared with alkaline fermentation,which provided abundant acidification substance for acidification bacteria.It also found that the activity of acidification bacteria was inhibited in the super-alkaline fermentation,which led to the lower SCFAs production than other conditions.However,the SCFAs and acetic acid were enhanced significantly in the super-alkali pretreatment alkali fermentation,which increased by 20.00%and23.00%respectively compared with the alkaline fermentation.Obviously,the super-alkali pretreatment alkali fermentation was more conducive to WAS anaerobic fermentation to producing acid.