The sizes of genome and chromosomes were respectively estimated with flow cytometry and image analysis in large yellow croaker(Larimichthys crocea).Genome size of large yellow croaker was estimated at 725.25±14.65 Mb.The relative area of chromosome ranged from 2.26%±0.08% to 4.83%±0.08%;the relative integrated optical density(IOD)ranged from 1.80%±0.32% to 5.04%±0.15%.Based on the relative IOD,the shortest physical length was estimated at 13.1±3.37 Mb for the 24th chromosome,while the physical length of the other chromosomes ranged from 24.4±6.21 Mb to 36.6±1.62 Mb.Linear correlation between the physical length and the relative area was observed,as well as linear correlation between the physical length and the relative length.The correlation coefficient for the physical length and the relative area was higher than that for the physical length and the relative length.The image of metaphase chromosome also showed that the optical density of chromosomes was not completely uniform with propidium iodide(PI)staining.The variation existed among non-homologous chromosomes,between sister chromatids,and among different regions of a chromosome.Above all,new parameters of chromosomes present in this paper will facilitate chromosome identification and pairing,as well as studies on genomics,in large yellow croaker.