Abstract: The chromosomal C-banding karyotype in the spermatogenesis of 2 species of Genus Asiotmethis , Uvarov 1943 from China were investigated. It was found that the diploid chromosome number of Asiotmethis zacharjini (Bei-Bienko, 1926) was 2n ♂ =18, the neo-X was a submetacentric chromosome and the rest were acrocentric chromosomes. C-banding pattern showed that all chromosomes presented a paracentromeric block, an interstitial C-band near the centrometic C-block and additional C-band in the distal region. And, the mechanism for sex determination lay in neo-XY(♂). In Asiotmethis jubatus (Uvarov, 1926), the diploid chromosome number was 2n ♂ =19. All autosomes and X-chromosomes were acrocentric with paracentromeric C-band only, and the mechanism for sex determination lay in XO(♂). The difference in heterochromatin content between the 2 species was significant at 0.05 level.