Abstract: The karyotypes of the first generation allotetraploid.allotriploid.new tetraploid and their parents-Japanese Phytophagous Crucian Carp (JPCC), Red Crucian Carp (RCC)were comparatively studied in this paper.Three parent fishes have the same diploid chromosome number of 100, but their karyotypes are differences in detail.The karyotype formula of JPCC(C.auratus cuvieri T.et S) is 12m+36sm+32st+20t, NF =148,there are one pair longest mark chromosomes in the submetacentric group.The karyotype formula of RCC (C.auratus red var.) is 20m+34sm+26st+20t, NF= 154.The karyotype formuls of the hybrid fish (JPCC×RCC) is 16m+35sm+29st+20t, NF =151.There is one longest mark chromosome similar to those of JPCC.It is a certificate that the karyotype of hybrid fish consists of one chromosome set from JPCC and the other chromosome set from RCC.The chromosome number of allotriploid (4N ♂×2N JPCC♀) was found to be 150.It is 1.5 bines more than that of their parents.The karyotype formula of allotriploid is 22m+53sm+ 45st+ 30t.One pair longest mark chromosomes in the submetacentric group demonstrated that the allotriploid karyotype was composed of two JPCC chromosome sets and one RCC chromosome set.The chromosome number of the first generation allotraploid and new tetraploid is 2 times more than that of their parent species, 4n=200.The karyotype formula of the first generation allotriploid is 32m+70sm+58st+ 40t, One pair longest mark chromosomes similar to those of JPCC were observed obviously.It confirms that the karyotype of the first generation allotetraploid comprises two chromosome sets of both JPCC and RCC Although the new tetraploid chromosome had not determined precisely,but three longest mark chromosome of JPCC in submetaphase chromosome had been observed obviously.Supposing its the karyotype of new tetraploid consists of 3 JPCC chromosome sets and 1 RCC chromosome set, It’s karyotype formula is 28m+71sm +61st+ 40t, The results confirmed the relationship and ploidy relation between the first generation allotetraploid, allotriploid, new tetraploid and their 3 parental species.