Abstract: With the construction and operation of cascade reservoirs in the upper reaches of Jinsha River, the problem of total dissolved gas(TDG) supersaturation caused by high dam flood discharge is more prominent, and the transport characteristics of supersaturated TDG in deep-water reservoirs under different flood discharge intensities are still unclear.In this paper, the transport law of supersaturated TDG in the Xiluodu-Xiangjiaba section under different flood discharge intensity scenarios was analyzed by combining prototype observation and a vertical two-dimensional mathematical model.The results showed that the discharge flow quantity and discharge duration of Xiluodu Reservoir drove the attenuation process of supersaturated TDG transport to the Xiangjiaba Reservoir area.The supersaturated TDG transport rate increased with the increase in discharge quantity and discharge time, and the fastest rate could reach 21.25 km/d.The increase in flood discharge from Xiluodu Reservoir led to an increase of the total amount of supersaturated TDG accumulated and the decrease of the attenuation rate in the Xiluodu-Xiangjiaba section.Under the design conditions, the attenuation rate of supersaturated TDG decreased with the increase in flood discharge time.After the Xiluodu Reservoir had discharged for about 24 hours, the TDG supersaturation state in the Xiluodu-Xiangjiaba section tended to be stable, and the minimum attenuation rate was only 0.74%/d.