Dissolved organic matter (DOM) from different biological treated wastewater in secondary effluent of different municipal wastewater treated plants are isolated and fractionated using resin adsorption into five different fractions: hydrophobic bases (HOB), hydrophobic acids (HOA), hydrophilic bases (HIB), hydrophilic acids (HIA) and hydrophilic neutrals (HIN). The characteristics of three dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) and disinfection by-products formation potential (THMFP) of each fraction are investigated. The objective of this study is to investigate the influence of different biological processes on THMs generation and transformation. The results show that for each municipal wastewater treated plant, HIA and HOA fractions content more fulvic-like acid and humic-like acid, which are the important matter to result the higher THMFP. THMFP of HIA rang from 736μg/L to 359μg/L in the secondary effluent. It shows that acidic organic matters are important THMs precursors, especially fulvic-like acids and humic-like acids. The Orbal oxidation ditch process can lead to the highest THMFP, and secondly is the Convert A2/O process.