Abstract: Karyotypes of two cyprinid fishes (Sinilabeo decorus tungting and Cirrhinus molitorella) and their hybrid (F1) were examined. The results of the karyotypie analysis are presented below:The diploid chromosome numbers of these three fishes are all 50. The karyotype of paternal fish(S. decorus tungting) is composed of 6 metacentric chromosome pairs, 8 submetacentric chromosome pairs, 5 subteloeentrie chromosome pairs and 6 telocentric pairs; while the karyotype of maternal fish (C. molitorella) consists of 10 metacentric chromosome pairs, 13 submetacentric chromosome pairs, 1 subtelocentrie chromosome pair and 1 telocentric pair. It is obvious that the karyotypic chromosome sets of the two parental fishes are different from each other.The karyotype of the hybrid (F1) is composed of 9 metacentric chromosome pairs, 13 submetacentric chromosome pairs and 3 subtelocentric pairs. It is different from either parental karyotypes. The karyotypic indices and the number of metacentric and submetacentric chromosome in F1 are nearly equal to those of its maternal fish, chromosome numbers of these two parts amounting to 88% of the total. Thus, F1 retains most of the chromosome homologous to its maternal fish.Some morphological descriptions on chromosome pairs above mentioned as well as the idiograms established on the basis of their karyotypes are given in this paper likewise.