Abstract:After the cell walls were degraded with enzymes and chromosomal samples were prepared, and then the number and modality of chromosomes in thirty-eightPhalaenopsis hybrids were analyzed. It was found that the chromosome ploidy displayed diversity in the analyzed varieties. Five varieties were used, of which three were tetraploid (2n=4x=76),and two were triploid (2n=3x=57).For the varieties bred abroad, fourteen were tetraploid, one was triploid and five were aneuploid. The number of the varieties bred at home was 13, ten were tetraploid and three were aneuploid. No diploid was observed. In addition, the chromosome length and modality also showed diversity among different hybrids, in which the genomes of twentyone consisted of small chromosomes (about 2.5 μm in length) only. In the other seventeen hybrids, however, big chromosomes (5-9.5 μm) were also observed besides the small ones. Some relation between the chromosome type and flower color was also observed. The chromosome ploidy, modality and sterility of different varieties in Phalaenopsis were discussed.