Abstract：A series of completely mixed anaerobic reactors were operated to investigate different alkalis (NaOH and Ca (OH)2) performance on sludge disintegration and organics hydrolysis and acidification in sludge alkaline fermentation systems. In addition, ammonia stripping was combined with alkali adjustment to observe the effect of NH4+ concentration on the hydrolysis and acidification effective of released organics. Results showed that at pH10, sludge disintegration as well as organics release, especially, volatile fatty acids (VFAs) was much higher in NaOH systems than that in Ca(OH)2 systems. However, part of soluble protein and PO43- were precipitated with Ca2+ in Ca(OH)2 systems. The PO43- concentration was less than 40mg/L in Ca(OH)2 systems. 43% of NH4+ was removed by ammonia stripping. The maximum hydrolysis and acidification performance was achieved in the NaOH adjustment and ammonia stripping system. The SCOD, protein, carbohydrate as well as total VFAs concentrations were 6732, 2029, 374 and 2545mg/L, respectively, and the NH4+ concentration was as low as 200mg/L. Analysis results also found that ammonia stripping could increase VFAs production by relieving the inhibition of NH4+ on acid-forming bacteria, and enhancing the fermentation of carbohydrate.