This review summarizes the research progress on doping modification of Ca₃Co₄O₉ thermoelectric (TE) materials. Calcium cobaltate (Ca₃Co₄O₉) is an excellent TE material with good oxidation resistance and high-temperature stability, but its low electrical conductivity limits its TE performance. Doping with other elements can increase carrier concentration, enhance electrical conductivity, and reduce thermal conductivity, thereby improving TE properties. The review covers various doping methods, including Ca site doping, Co site doping, and double doping of Ca and Co sites with elements such as alkali (earth) metals, transition metals, rare earth metals, and main group metals and non-metals. The current challenges and development trends of doping modification of Ca₃Co₄O₉ materials are discussed to provide a theoretical basis for further development and application of TE materials. Thermoelectric materials convert thermal and electrical energy via the Seebeck effect. The figure of merit (ZT) is a key parameter for evaluating TE performance, defined as ZT = S²σT/κ, where S is the Seebeck coefficient, σ is electrical conductivity, and κ is thermal conductivity. High ZT values require high Seebeck coefficients, high electrical conductivity, and low thermal conductivity, which are interrelated. Improving ZT involves optimizing electrical and thermal properties to decouple these parameters. Ca₃Co₄O₉ has a monoclinic structure with alternating insulating Ca₂CoO₃ and conductive CoO₂ layers along the c-axis. The Ca₂CoO₃ layer is insulating, while the CoO₂ layer provides holes. Despite its advantages, Ca₃Co₄O₉ has low electrical conductivity, limiting its TE performance. Current research focuses on improving TE performance through doping. Preparation methods include solid-state reaction and sol-gel methods. Solid-state reaction involves mixing raw materials and high-temperature calcination, while sol-gel involves dispersing raw materials in a solvent and hydrolyzing to form active monomers. Challenges include long reaction times and large particle sizes. Future research aims to enhance TE performance through doping and optimize preparation methods.This review summarizes the research progress on doping modification of Ca₃Co₄O₉ thermoelectric (TE) materials. Calcium cobaltate (Ca₃Co₄O₉) is an excellent TE material with good oxidation resistance and high-temperature stability, but its low electrical conductivity limits its TE performance. Doping with other elements can increase carrier concentration, enhance electrical conductivity, and reduce thermal conductivity, thereby improving TE properties. The review covers various doping methods, including Ca site doping, Co site doping, and double doping of Ca and Co sites with elements such as alkali (earth) metals, transition metals, rare earth metals, and main group metals and non-metals. The current challenges and development trends of doping modification of Ca₃Co₄O₉ materials are discussed to provide a theoretical basis for further development and application of TE materials. Thermoelectric materials convert thermal and electrical energy via the Seebeck effect. The figure of merit (ZT) is a key parameter for evaluating TE performance, defined as ZT = S²σT/κ, where S is the Seebeck coefficient, σ is electrical conductivity, and κ is thermal conductivity. High ZT values require high Seebeck coefficients, high electrical conductivity, and low thermal conductivity, which are interrelated. Improving ZT involves optimizing electrical and thermal properties to decouple these parameters. Ca₃Co₄O₉ has a monoclinic structure with alternating insulating Ca₂CoO₃ and conductive CoO₂ layers along the c-axis. The Ca₂CoO₃ layer is insulating, while the CoO₂ layer provides holes. Despite its advantages, Ca₃Co₄O₉ has low electrical conductivity, limiting its TE performance. Current research focuses on improving TE performance through doping. Preparation methods include solid-state reaction and sol-gel methods. Solid-state reaction involves mixing raw materials and high-temperature calcination, while sol-gel involves dispersing raw materials in a solvent and hydrolyzing to form active monomers. Challenges include long reaction times and large particle sizes. Future research aims to enhance TE performance through doping and optimize preparation methods.