Abstract: The karyotypes of Ctenopharyngodon idellus, Megalobrama terminalis and their F1 hybrid were studied with routine air-drying method. The results show that the female and male parents have the chromosome number of 48 and the F1 hybrid has a chromosome number of 72. Comparison of karyotypes between the parents and the F1 hybrid demostrates that the hybrid is a triploid which received 48 chromosomes from the maternal and 24 chromosomes from the paternal fish.