The major concern of this study has been focused on the cytotaxonomic position of six species of the Korean Orthoptera. The chromosome number and karyotype of six species in the Korean Orthoptera were observed by using squash techniques and lacto-propionic orcein stain in order to define species relationships between them. Several characters, numerical and morphological differences were shown in the chromosome between the species at the stages of spermatogonia metaphase and spermatocyte metaphase. The result were as follows, 1. The pattern of basic chromosome number in these species was divided into two groups; Acrida late MOTSCHULSKY, Oxya velox FABRICIUS, Acryptera coreana SHIRAKI, and Atractomorpha bedeli BOLIVAR were 20, 23, in the diploid chromosome number but Gampsocleis sedakovi obscura WALKER and Conocephalus gladiatus REDTENBACHER were 31. 2. The sex chromosome of five species(A. lata M., O. velox F., A. coreana S., G. sedakovi obscura W., C. gladiatus R. were XO type, but A. bedeli B.) was XY type. 3. Three species(A. lata M., A. bedeli B., A. coreana S.) showed the supernumerary chromosome in the spermatogonial metaphase. 4. C. gladiatus R. showed the fragment chromosome in the spermatocyte metaphase. 5. The shape of chromosome of these species in divided into two groups; the chromosome of Locustidae group were rod or fusiform in shape at the spermatogonia metaphase. In the Tettigoniidae, they were round or oval. Considering the above results, the Locustidae and the Tettigoniidae were differently divided by morphological characters of external feature, in addition to, cytotaxonomic were similar to.