Abstract: LC-MS/MS was applied to the determination of 5 chlorophenols in water with microextraction of amphiphilic polymeric ionic liquid membrane. Shim-pack XR-ODS Ⅱ chromatographic column was used as stationary phase, and the mixture of 0.005 mol·L^-1 ammonium acetate solution and methanol-acetonitrile (1+4) solution mixed in different ratios was used as mobile phase in gradient elution. ESI^- and multi-reactions monitor mode were adopted in MS/MS. Detection limits (3S/N) of the method were in the range of 0.33-5.4 ng·L^-1. Values of recovery found by standard addition method were in the range of 86.4%-99.1%, with intra-day RSD's (n=6) in the range of 0.80%-8.2% and inter-day RSD's (n=6) in the range of 1.7%-8.7%.