The abundance of chloramphenicol (CAP), a representative antibiotic, was investigated in drinking water sources of the Yangtze River Delta region with detection frequencies of 16-45%. Considering the abuse of CAP, understanding its fate in the water treatment process was necessary. The kinetics and by-products formation of 5 mg L-1 CAP by means of chlorination and photocatalytic oxidation were studied. The degradation of CAP follows approximately a pseudo-first-order kinetics for both chlorination and photocatalytic oxidation, with pseudo first-order rate constants k(obs) = 0.164 min(-1) and k(obs) = 0.031 min(-1) respectively. The reaction rate of CAP chlorination is higher in alkaline solution, while the extent of degradation for photocatalytic oxidation is much greater at pH 4. Transformation intermediates were identified using liquid chromatography-tandems mass spectrometry (LC-MS/MS) and the possible degradation pathways were proposed. Furthermore, disinfection by-products (DBPs) formation potentials were studied by gas chromatograph-mass mass spectrometry GC-MS/MS.