The five current methods of mining natural gas hydrates are summarized with focus on the analysis of CO₂ replacement mining and solid mining methods， and by analyzing the advantages and disadvantages of the two mining methods， a new approach， by which water jets erodes and breaks ocean gas hydrates in combination with CO₂ replacement， is proposed for the exploitation of natural gas hydrates， The mined-out area formed by erosion and breaking of water jets in the hydrate reservoir can provide better storage space for CO₂， increase its interaction area with the reservoir， and improve the replacement efficiency. The stored CO₂ hydrate can also increase the stability of the hydrate reservoir， providing good complementary effect. The experimental results show that during the entire replacement process， the CH₄ replacement rate in the reservoir containing the mined-out area is 24.3%， and the CO₂ storage rate is 22.1%； while the CH₄ replacement rate in the intact reservoir is 15.3%， and the CO₂ storage rate is 20.9%； indicating that the replacement rate increases about 59%， the storage rate increases about 5.7%. The function of the goaf is mainly reflected in increasing the injection volume of the hydrate replacement medium.