Abstract: It's the first time that the study on mitotic karyotype of ghost moth was reported in this paper. Using an acetic acid dissociation and air-drying technique, we have studied the mitotic chromosomes of two species of ghost moth in Ynnan Province of China, Hepialus zhayuensis Chu et Wang and Hepialus sp. (Lepidoptera, Hepialidae).Their diploid chromosome number is 2n=64. The holocemtric is clearly shown on chromosomes at early mitotic metaphase. However, in mitotic metaphase and later metaphase, the primary centromeres (primary consirictions) can be seen on each chromosome. A pair of typical heteromorphic sex chromosomes were found in the male karyotype of two species. X-chromosome is provided with metacentric or submetacentric and more slightly seained. Y-chromosome is deeply stained and bigger than the other chromosomes in the karyotype.In male interphase cell, one heteropycnotic sex chromatin body can be found distinctly. That is the Y-chromosome.