Abstract:The karyotypes of four Cymbidium sinense cultivars were studied. Somatic chromosome numbers of cultivars ‘Qijianheimo＇ and ‘Qijianbaimo＇ are 2n=40 （diploid）, the karyotype formulas being 2n=2x=40=30m＋10sm and 2n=2x=40=2M＋36m＋2st, respectively. However, the chromosome number of cultivars ‘Jinzui＇ and ‘Yinbian＇ are 2n=41 and are aneuploid. The chromosome structures of all the four cultivars mainly consist of metacentric chromosomes. According to Stebbins＇ classification of karyotypic asymmetry, the karyotype of cv. ‘Yinbian＇ is of 1B type, and that the other three of 2B type.