Abstract: Ecological experiment was conducted to study the allometric growth of chum salmon (Oncorhynchus keta Walbaum) yolk-sac larvae and its significance in adaptation in early life stage. The results indicated during the yolk-sac larvae stage organs associated to feeling, breathing, feeding and swimming developed and differentiated rapidly, and exhibited allometric patterns. Head and tail length exhibited positive allometric growth, and trunk exhibited negative allometric growth, body height have increased positively at first, then negatively. As for dimensions of organs in head, eye diameter, mouth width, rostrum length and post-eye head length, exhibited positive allometric increase. As for swimming organs, pectoral fin, pelvic fin, dorsal fin, anal fin, base of dorsal fin, base of anal fin and caudal fin, exhibited positive allometric growth; but adipose fin exhibited negative allometric growth. In addition, pelvic fin exhibited positive allometric growth both before and after the growth inflexion point, 25.31 mm in full length and 12 days after hatching. The fast development of feeling, feeding, breathing, swimming and other organs in yolk-sac larvae of chum salmon, increases larval survival ability at the early stage in the shortest possible time, and has important ecological significance to adapt the complex external environment.