Abstract: Four Liangshan Semifine-Wool Sheep and four Tibetan Sheep were used to compare the karyotypes, which were employed on slides obtained from the peripheral blood cell culture. The result showed that: the karyotype of ram was 54, XY; and the ewe’s was 54, XX.In the two breeds,the frequency of numerical chromosome change were 12.00% and 17.60%, and the frequency of chromosomal structural change were 33.00% and 32.25%;the type of the chromosomal structural change includ chromosome break,chromatid break and centric change;Some break points of chromosomal structural change were correspondence with the loci of specific Ag-NORs; Some homologues had the different length in the two breeds, and this phenomenon in Liangshan Semifine-Wool sheep was more significant than in Tibetan sheep.