Evaluating anaerobic biodegradability of sludge and then identifying the stabilization of di-gestate is necessary in sludge treatment and disposal.48 sludge samples from 24 typical waste water treatment plants(WWTPs)in 11 provinces in China were selected to investi-gate the relationship between Biochemical Acidogenic Potential(BAP)test and Biochemical Methane Potential(BMP)test.The volatile fatty acid(VFA)production obtained from BAP tests was found linearly related to the ultimate methane production from corresponding BMP tests.Satisfying results were obtained with Pearson correlation coefficient as 0.929 and R2 value as 0.76.Furthermore,the physio-chemical characteristics(FCI,SUVA254,Et/E6)of supernatant,which were associated with humic-like substances(HS),were investigated be-fore and after BMP tests.Through which a new criterion(FCI＞1.50,SUVA254＞1.10,E4/E6＜4.0)was proposed to evaluate the stabilization level of anaerobic digested sludge.