Carbon emission reduction and clean energy development are urgent demands for mankind in the coming decades. Exploring an efficient CO2storage method can significantly reduce CO2emissions in the short term. In this study, we attempted to construct sediment samples with different residual CH4hydrate amounts and reservoir conditions, and then investigate the potentials of both CO2storage and enhanced CH4recovery in depleted gas hydrate deposits in the permafrost and ocean zones, respectively. The results demonstrate that CO2hydrate formation rate can be significantly improved due to the presence of residual hydrate seeds; However, excessive residual hydrates in turn lead to the decrease in CO2storage efficiency. Affected by the T-Pconditions of the reservoir, the storage amount of liquid CO2can reach 8 times that of gaseous CO2, and CO2stored in hydrate form reaches 2–4 times. Additionally, we noticed two other advantages of this method. One is that CO2injection can enhance CH4recovery rate and increases CH4recovery by 10%–20%. The second is that hydrate saturation in the reservoir can be restored to 20%–40%, which means that the solid volume of the reservoir avoids serious shrinkage. Obviously, this is crucial for protecting the goaf stability. In summary, this approach is greatly promising for high-efficient CO2storage and safe exploitation of gas hydrate.