Experiment object was Escherichia coli. The objective of present study is to investigate the removal characteristics of Escherichia coli, as the disinfection by-products precursors during chlorination process by potassium permanganate preoxidation process under different conditions. Evaluated factors included potassium permanganate concentrations, chlorination time, pH value, preoxidation time, reaction temperature. Results showed that the concentration of dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), 1,1,1-trichloropropanone (1,1,1-TCP) and trichloroacetaldehyde (CH) initially decreased and then increased, and 1,1-dichloropropanone (1,1-DCP) initially increased and then decreased, trichloromethane (TCM) decreased gradually with increased potassium permanganate concentrations. In this study, the concentration of DCAN, TCAN and 1,1,1-TCP decreased to the lowest and achieved optimized removal efficiency with the potassium permanganate concentration reached 2mg/L; With the prolonged chloration time, the concentration of TCAN, 1,1-DCP increased gradually. The concentration of DCAN, CH, 1, 1, 1-TCP initially increased and then decreased. The concentration of TCM initially increased and tend to be stable; With the increased of pH from 5 to 9, the concentration of 1,1,1-TCP、TCAN decreased gradually. The concentration of DCAN initially decreased and then increased. The concentration of 1,1-DCP、CH initially increased and then decreased; With the prolonged pre-oxidation time, the concentration of TCAN, DCAN, TCM decreased gradually. The concentration of 1,1-DCP, 1,1,1-TCP initially increased and then decreased. The concentration of CH initially increased and tend to be stable; With the increased of temperature, the concentration of 1,1-DCP、DCAN increased gradually. The concentration of 1,1,1-TCP decreased gradually. The concentration of TCAN、TCM initially increased and then decreased. The concentration of CH initially decreased and then increased. In conclusion, to attain optimized removal efficiency for the disinfection by-products precursors of Escherichia coli. It is suggested from this study that the potassium permanganate concentration should reach 2mg/L, under chloration time of 48h, alkaline condition (pH > 8), and pre-oxidation time of 30min.