Abstract: Combination of hybridization and polyploidy have always been important means of Citrus breeding. Both allotetraploid and allodiploid of C. grandis‘Shatianyou’× C. ichangensis were obtained by the above two methods. The genetic composition of these materials were analysed through karyotype analysis and genomic in situ hybridization（GISH）. The chromosome types，number and distribution of satellites，arm ratio，relative length of chromosome of 11 materials were compared and showed karyological variations. The exsitence，number and distribution of the satellite had obvious diversity. Compared with the parents，the allotetraploid and allodiploid had no significant chromosome structural variation. However，different karyotypes showed that there existed chromosome recombination and slight variation of chromosome structure during the process of hybridization and polyploidy formation. The results of GISH revealed that allotetraploid（CSY）and allodiploid（SY）indeed are the hybrid of C. grandis‘Shatianyou’and C. ichangensis. Meanwhile the number of chromosomes with stronger signals on thetop region was the half of somatic cell，indicating they could be derived from the probe parental chromosomes. The chromosomes origin of CSY and SY can be basically distinguished by GISH. The preliminary analysis of karyotype and GISH of the different ploidy materials provided cytogenetics data for Citrus genetics and breeding research. Moreover，the application of genomic in situ hybridization technique in Citrus played an important role for the Citrus genome composition in the future.

Key words: Citrus, tetraploid, karyotype, genomic in situ hybridization（GISH）