Abstract: The development of diagnostic method of canine distemper（CD ） in cell biology and molecular biology was summarized in this paper. In the cell biology aspect, the diagnosis of CD was mainly depended on virus isolation and culture,artificial replication experiment, election microscope examination, inclusion body examination, specific antigen and antibody examination and so on. Along with the development of molecular biology, nucleic acid hybridization and RT-PCR diagnosis of canine distemper virus （CDV） have been established. These methods in sensitivity and specificity were higher compared with the traditional methods, especially in the earlier period of CDV infection when the animal body can＇t develop an immune response.