The gas solubility in the aqueous solution surrounded the hydrate particle are important for determining hydrate growth rate and stability, which are the main concerns for marine CCUS. This work conducted a series of experiments to study the influence of temperature, pressure, and salinity on CO2 solubility in wider temperature and pressure range, ranging from liquid-gas (Lw-V) two-phase system, hydrate-liquid-gas (H-Lw-V) three-phase equilibrium system, to hydrate stability zone. The CO2 solubility curves in wider temperature and pressure range from Lw-V two-phase system to hydrate stability zone are achieved in this work. Meanwhile, the experimental results show that the CO2 solubility in brine at H-Lw-V three-phase equilibrium conditions is higher than that in deionized water, while it doesn’t linearly increase with the increase of salt concentration.