Abstract: The power sector is the sector with the highest carbon emission in China. Under the background of dual-carbon goal, China’s coal power industry should implement large-scale emission reduction efforts. Compared with traditional coal-fired power generation, coal-based gas power generation has a certain carbon reduction potential, but its carbon emissions and cost assessment are still insufficient. Therefore, based on the perspective of the whole life cycle, the cost and carbon emission accounting model considering power equalization is proposed, that is the amount of CO₂ emitted and the cost of producing 1 kWh of electricity by different technologies to measure the economic feasibility of different coal-based gas-fired power generation technologies. The results show that in terms of carbon emissions, the carbon emissions per unit of electricity for ultra-supercritical coal-fired power (USC-PC), coal underground gasification combined cycle (UGCC), coal integrated gasification combined cycle (IGCC), coal bed methane-combined cycle gas turbine (CBM-CCGT) and substitute natural gas-combined cycle gas turbine (SNG-CCGT) are 1 009.148, 1 028.829, 1 033.973, 471.403, and 1 140.712 g/kWh, power generation efficiency, energy conversion rate of coal-to-gas and low calorific value of coal have great influence on carbon emission of coal-based gas power generation. In terms of cost, the levelized cost of electricity of UGCC, CBM-CCGT, SNG-CCGT, IGCC and USC-PC are respectively 0.307, 0.306, 0.343, 0.335 and 0.331 yuan/kWh. Coal transportation and coal price have a significant impact on the cost of coal-based gas power generation. After the installation of carbon capture and storage (CCS), the carbon emissions of UGCC are reduced and the cost is increased. After the carbon emissions are monetized, the total cost of actual UGCC is increased from the original 0.387 yuan/kWh to 0.560 yuan/kWh. Assuming that fluidized coal gasification is combined with UGCC for power generation, the total cost of fluidized UGCC power generation is 0.052 yuan/kWh lower than that of traditional UGCC. After installing CCS, the total cost of fluidized UGCC power generation increases from 0.334 yuan/kWh to 0.515 yuan/kWh. Therefore, it is suggested to promote technological progress to improve power generation efficiency and gas conversion efficiency and combine CCS technology to reduce carbon emissions of coal-based gas power generation technology, encourage companies to invest in cleaner equipment by internalizing environmental impact, and encourage policies such as clean coal price subsidies for low-carbon enterprises.