C-banding karyotype of Brassica campestris var. pekinensis was analysed and chromosomal location of 45S and 5S rDNAs using FISH was determined. The somatic chromosome number was 2n=20. The chromosome complement was composed of six pairs metacentrics (1, 3, 4, 5, 6 and 10), two pairs submetacentrics(2 and 7), and two pairs subtelocentrics (8 and 90. The size of chromosomes ranged from 1.00 to 2.06 μm. Chromosome 2 was identified as a satellite chromosome. The dark-stained heterochromatic spots were distinctly observed in prometaphase chromosomes. All the chromosomes except chromosome 2 had C-bands at the centromeric regions, while the satellite of chromosome 2 showed thick C-band,. The sequence of 5S rDNA was 491 bp long and the initial sequence was CAT. Three pairs of 45S and two pairs of 5S rDNA signals were detected with FISH.