2,3,5,6-Tetrachloropyridine (TCP) was prepared by cyclization reaction of 2,2,4-trichloro-4- cyanomethylbutyrate (MTCB) synthesized from methyl trichloroacetate (MTCA) and acrylonitrile (AN). The results of GC/MS showed that the product of cyclization reaction was TCP. The optimum reaction conditions were phosphorus oxychloride and MTCB in molar ratio 2:1, reaction temperature 140℃ and reaction time 4 h. The yield of TCP was 93% under these conditions. Based on works aforementioned, the possible cyclization mechanism of MTCB was discussed.