Four Miscanthus species, M. sinensis, M. floridulus, M. sacchariflorus and M. lutarioriparius, including 36 germplasms were selected for first chromosomal ploidy determination by flow cytometry and then for the karyotype analysis using tableting method. The results showed: 1) The order from larger to small of fluorescence values of the four Miscanthus species is M. lutarioriparius, M. sinensis, M. floridulus, M. sacchariflorus with no significant differences among interspecific. The largest coefficient of variation of the fluorescence value, 37.73%, is from M. lutarioriparius, while the smallest, 4.41%, is from M. floridulus. This indicated that M. lutarioriparius is the most ploidy various, while the M. floridulus is the most stable ploidy among the four studied scpecies. 2) Miscanthus owns x=19 basic chromosome numbers, and all of the 36 germplasms, there are 33 diploids (2n=2x=38), 2 triploids (2n=3x=57) and 1 tetraploid (2n=4x=64), which indicate that the Miscanthus is mainly diploid, occasionally triploid and tetraploid in nature. 3) The four Miscanthus species showed significant difference in karyotype parameters, localized mainly at metacentric chromosome and submetacentric chromosome. All of M. sinensis and M. floridulus accession show “2B” karyotype type and M. sacchariflorus and M. lutarioriparius show “2C” type. This indicated that M. sinensis and M. floridulus was close genetic relationship, and M. sacchariflorus and M. lutarioriparius had close genetic relationship. 4) The cluster analysis showed that the 36 Miscanthus germplasms could be clustered into three groups: M. sinensis and M. floridulus in group 1, M. sacchariflorus and M. lutarioriparius as group 2 and the polyploidy as group3. This work provided a cytological basis for the genetic and phylogenetic evaluation of Miscanthus.