| The dune grass Leymus mollis (Trin.) Pilger, a perennial tetraploid species in Leymus (Triticeae: Poaceae) (2n = 4x = 28, NsNsXmXm), which grows mainly along sea coasts and in inland dry areas, is a valuable genetic resource for wheat breeding as a tertiary gene pool. In order to provide the theory basis for the developing, screening and identifying more potential and useful germlasm types of common wheat and L.mollis, the chromosome constitution of common wheat 7182, L.mollis and wheat-L.mollis derivatives were analyzed by cytogenetic observation and identification, sequential fluorescence in situ hybridization (FISH) - genomic in situ hybridization (GISH), functional molecular marker technologies. The standard FISH karyotype patterns of common wheat cv. 7182 was painted using two probes Oligo-pTa535 and Oligo-pSc119.2. Preliminary karyotype analysis of L.mollis was carried out and its karyotype formula was 2n = 4x = 28 = 22m (6sat) + 6sm, m means metacentric chromosome, sm means submetacentric chromosome, sat means satellite chromosome, belonging to "IIA" of Stebbins. Furthermore, the chromosome constitution of wheat-L.mollis derivatives M47 and M39 were identified, which can be expressed as 2n = 56 = 42T.a + 14L.m and 2n = 56 = 44T.a + 12L.m (where T.a = T. aestivum chromosomes; L.m = L. mollis chromosomes), respectively.