Abstract: A larger number of fertilized eggs with attaching filaments attached to some seaweeds were collected in the southern Yellow Sea (33°49′N, 122°10′E). In order to make an accurate identification of the fish eggs, light microscope, scanning electronic microscopy (SEM), and genetic analysis were used. Under light microscope, the egg is an oblated and agglutinated demersal with a narrow perivitelline space; eggs ranged in diameter from 1.95 to 2.38 mm with a mean of 2.18 ± 0.03 mm; their membrane are smooth and they have 5 to 7 cannular keratose egg-filaments; the oil globules are multiple, ranged in diameter from 0.05 to 0.50 mm and in number from 7 to 145 with a mean of 28±2, the position of them migrate during embryonic development; the yolks are ivory-white with no segments, ranged in diameter from 1.00 to 2.30 mm with a mean of 1.90 ± 0.03 mm; the development phases of the embryo are variable. So they were identified as the eggs of one Beloniformes. Under scanning electric microscopy (SEM): the egg’s micropyle is apparent, it lines in the middle of the attaching filaments and the outer diameter of it is about 12.3μm; the pores on the envelope are unapparent, but there are many grain substances on it, with the density was about 50 pieces/100μm2. The result of genetic analysis conveyed that in partial sequences of mtDNA Cyt b gene there were no variable sites between the eggs and Japanese halfbeak, and the genetic distance between them was 0, however, many variable sites between the eggs and the other fishes of Beloniformes were exised, the variable rate was 18.72-21.3％, and the genetic distance between them were 21.9-26.4％. The result of Neighbor-joining(NJ) molecular phylogenetic tree also indicated that the eggs and the Japanese halfbeak were assembled at the same embranchment, they shared one haplotype, but the eggs were assembled at different embranchments with the other species of Beloniformes so the fish eggs were alienated from them. Based on the results above, it is suggested that the fish eggs to be Japanese halfbeak.