Abstract: Oxy-fuel combustion is a promising in-combustion carbon capture technology for low-carbon utilization of fossil energy, offering low CO2 capture cost and strong retrofitting adaptability. This paper reviews the energy consumption and exergy loss distribution across key units, revealing significant disparities among the air separation unit (ASU), CO2 compression and purification unit (CPU), and boiler, as well as their cross-unit coupling mechanisms. The effects of operating parameters, flue gas recirculation modes, and fuel properties on energy consumption are discussed.Recent advances in energy consumption optimization are summarized from two perspectives. At the unit level, innovations in air separation processes, oxygen purity adaptation, and CPU process improvements have reduced the energy consumption of individual components. At the system level, cross-unit waste heat recovery and energy cascade utilization have controlled the efficiency penalty of carbon capture to 7~8 percentage points for atmospheric oxy-fuel combustion systems. Furthermore, pressurized oxy-fuel combustion and staged pressurized oxy-fuel combustion, which employ combustion pressure as a global control parameter to reshape the energy consumption distribution, can further reduce the efficiency penalty by 1~2 percentage points. Finally, future research directions are outlined, including the integration of oxy-fuel combustion with grid peak regulation and multi-energy complementarity with renewables