Abstract: To address the demands for deep peak shaving and low-carbon retrofitting of coal-fired power plants, a molten salt thermal energy storage-assisted carbon capture, utilization and storage (CCUS) coal-fired power generation system was proposed. Models of the thermal energy storage system and carbon capture system were developed using EBSILON and ASPEN PLUS software, respectively, enabling full-process simulation of a 630 MW unit. The economic was evaluated to study the mechanisms of thermal storage systems in enhancing peak-shaving capabilities and the impact of CCUS systems on carbon emissions. Results show that the thermal energy storage system adopts a dual-tank molten salt configuration with a designed storage capacity of 875 MW·h, achieving a thermal efficiency of 95%. The storage tank volume is 6 730 m³, with a unit cost of 175 yuan/(kW·h). Under various operating conditions, the CO₂ capture rate of the CCUS system remains consistently at 90%, with an annual emission reduction of 1.654 6 million tons. After retrofitting, the unit's peak-shaving depth decreases from 40% to 0%, while the peak-shaving capacity increases by 180.1 MW, and the levelized cost of electricity (LCOE) changes from 0.374 8 yuan/(kW·h) to 0.365 3 yuan/(kW·h). The total project investment amounts to 2.374 billion yuan. Under the carbon trading price of 98 yuan/t, the net present value reaches 573 million yuan, with a payback period of approximately 19 years. Sensitivity analysis reveals that for every 10 yuan/t increase in carbon price, the LCOE decreases by 0.002 7 yuan/(kW·h), and for every 50 yuan/(MW·h) increase in peak-shaving compensation price, the LCOE decreases by 0.004 yuan/(kW·h). This study provides a technical pathway and economic assessment framework for the synergistic development of flexibility retrofitting and low-carbon transformation in coal-fired power units.