Abstract: HPLC was applied to the determination of 2-chloro-5-trichloromethylpyridine (TCMP),an important intermediate for the synthesis of the weedicide haloxy-fop-methyl.The conditions of the method were studied in detail,and the optimum conditions found were as follws.Zorbax eclipse XDB-C18 was used as RP-chromatographic column,a mixed solution of acetonitrile and water in the proportion of 30 to 70 was used as mobile phase,flow-rate of the mobile phase was 1 mL·min-1.UV-detection at 240 nm was adopted in the measurement.Linear relationship between the peak area and concentration of TCMP was obtained in the range of 0.004 to 0.020 mg·L-1 (r=0.998 4).Recovery test was performed and a result of average recovery of 99.05% was obtained.In the analysis of some substantial samples,TCMP was determined by this method together with two main by-products,ECMP and CCMP obtained simultaneously in the synthesis of TCMP.