Ca3Co4O9 has become a research hotspot in the field of oxide thermoelectric materials due to its good chemical stability, low cost and nontoxicity. However, the practical application of Ca3Co4O9 is seriously hindered by its difficult synthesis, low density and low conversion efficiency. In this paper, the research progress of Ca3Co4O9 with layered structure is summarized and analyzed from the aspects of synthesis method, modification method and sintering process, and some suggestions for the future research and development of Ca3Co4O9 are put forward.