Abstract: The karyotype and chromosome number of Catalpa duclouxii Dode, were analysed on meristematic cell of root tips.The result has shown that the chromosome number in each somatic cell is 2n=40, and all chromosomes have median centromeres.The 15th pair is SAT-chromosome.According to the classification made by Levan et al., the karyotype formula is K(2n)=40=38m+2m₁₅^sat. According to the ratio of chromosome Iength(largest/smallest > 2) and the proportion of chromosomes with arm ratio < 2 in the complement, the karyotype of Catalpa duclouxii Dode is Stebbins' "1B" of symmetrical karyotype.