Abstract: This paper investigates the relationship between disinfection by-products (DBPs) formation pathways and components with various chemical characteristics of dissolved organic matter (DOM) in a Karst plateau reservoir, Aha Reservoir in Guiyang City. Using DOM obtained from the reservoir, several chemical characterization approaches, including UV-Vis scanning, FTIR, and 3D-EEM fluoresce, were applied to investigate the potential contribution of different DOM fractions (separated by XAD resin) in the generation of the carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs).The results indicated that the aromaticity of different DOM fractions followed in the decreasing order:hydrophobic neutral (HON)>hydrophilic base (HIB)>hydrophobic acid (HOA)>hydrophilic neutral (HIN)≈hydrophilic acid (HIA)>hydrophobic base (HOB). Both hydrophilic and hydrophobic fractions possessed similar DBP formation potentials (DBPFPs). In detail, HON had the highest DBPFP, followed by HIB and HOA. The majority of halogenated active sites in HIB and HOA originated from protein in algal organic matter and fulvic acid, while the DBPFP of HON is likely responsible for its high aromatic and unsaturated structures. The decreasing DBPFP corresponded with elevated aliphatic hydrocarbon structures found in HIN and HIA. For C-DBPs, less difference was observed for THMs and HAAs of all DOM fractions. Haloacetonitriles accounted for 80% of N-DBPs, which was mainly contributed by hydrophobic parts. The DBP formation pathway was satisfactorily supported from chemical functional groups and characteristic peaks by UV-Vis, FTIR, and 3D-EEM, respectively.