The karyotypes of three species of Tetraodontiformes fishes were analyzed. The PHA and colchicine were injected in vivo,and kidney cells were collected and treated with lower osmotic pressure and air-drying technique. The results showed that these three marine species had diploid chromosome karyotypes,and all did not contain satellite chromosome,secondary constrictions and sex chromosome. The karyotype formula were as follows: the karyotype of Monacanthus chinensis was 2n = 34,34t,NF = 34; the karyotype of Takifugu xanthopterus was 2n = 44,12m + 8sm + 24t,NF = 64; and the karyotype of T. rubripes was 2n = 44,14m + 6sm + 24t,NF = 64; We also compared the karyotypes of the related fishes in the order of Tetraodontiformes.