Abstract: High-temperature depleted gas fields are characterized by large burial depth, low permeability, and abundant geothermal energy, which can be exploited via recycling CO₂. To realize the field application of CO₂ and the efficient exploitation of geothermal energy, CO₂ can be injected before geothermal development to improve natural gas recovery and restore gas reservoir pressure. However, there is still a lack of systematic research on the process of subsurface CO₂ geothermal development, the thermal cycle of CO₂ power generation on the ground has not been reported in the literature, and the economics of CO₂ geothermal development and power generation need to be analyzed in details. For this reason, firstly, a geothermal exploitation model is established based on the conditions in a typical high-temperature depleted gas field, and an analysis is performed on the temperature and pressure changes and geothermal development rate of the reservoir in each stage of CO₂ geothermal development throughout the whole process. Then, this paper proposes the organic Rankine cycle and CO₂ direct cycle power generation methods, and optimizes the thermal cycle process of power generation. Finally, the cost and economics of CO₂ geothermal development and power generation are evaluated using the levelized power generation cost calculation method. The results show that for the depleted gas reservoir with a volume of 1 500 m×1 000 m×50 m at 120℃, 11.75×10⁸m³ CO₂ can be stored during the enhanced gas recovery and pressure build-up stage; the method of CO₂ injection and production has a great influence on CO₂ storage in the geothermal development stage. However, the CO₂ geothermal development rate can be maintained at about 10 MW within 30 years. The organic Rankine cycle system has a maximum power generation rate of 132.7 kW, while the CO₂ direct cycle system can be up to 718.5 kW; the purchase cost of CO₂ has a great impact on the cost of power generation, and when the price is lower than 7-10 US dollars/t, the cost of geothermal power generation via recycling CO₂ injection from low-permeability depleted gas reservoirs is equivalent to the cost of existing coal-fired power generation.