Abstract: During the flood season, flood discharge of dams in the Changjiang River could cause gas supersaturation of the downstream water bodies, which might disturb or damage the normal life activities of aquatic organisms living in the downstream area.This paper aimed to study the impact of gas supersaturation on Carassius auratus,one of the important economic species in the Changjiang River, and provide theoretical basis for the protecting of aquatic organism resources in the Changjiang River.Carassius auratus at different early development stages, namely fertilized eggs, larvae, small juveniles and large juveniles, were exposed to water with 110%,120%,130%,and 140% gas saturation.The fertilized eggs were exposed until hatching; larvae, small juveniles and large juveniles were exposed in the gas supersaturation water for 96 h.Results showed that the hatching rate was ranged from 61.43% to 72.86%,and there were no significant difference between the experimental groups and the control group.All the experimental fish showed different degrees of symptoms of gas bubble disease; the mortality of experimental fish increased with the increase of exposure time and the degree of gas supersaturation; the mortality of large juvenile fish was the highest at each saturation, followed by small juvenile fish, and larvae were the lowest.With the increase of gas supersaturation, the semi-lethal time of juvenile fish decreased significantly.