As an emerging nucleic acid vaccine technology， mRNA vaccines have undergone rapid development and achieved commercial application since the COVID-19 pandemic. Owing to their flexible design， short development cycles， and ability to induce both humoral and cellular immune responses， this technology has become an important platform for infectious disease prevention and control as well as cancer immunotherapy. However， insufficient stability remains a critical bottleneck hindering the widespread application and industrial development of mRNA vaccines. The mRNA molecule itself is susceptible to degradation due to physical， chemical， and biological factors， while the lipid nanoparticle delivery system is prone to issues such as particle aggregation， increased particle size， structural changes in the lipid membrane， and mRNA leakage during storage， freeze-thaw cycles， and transportation， thereby compromising the immunogenicity and safety of the vaccine. This review focuses on the stability of mRNA vaccines， analyzing the potential mechanisms of mRNA degradation， lipid nanoparticle instability， and the decrease in vaccine activity during production， transportation， and storage， and summarizing the key factors affecting their physical， chemical， and functional stability from the perspectives of molecular structure， sequence optimization， chemical modification， delivery systems， manufacturing processes， and storage conditions. By reviewing the latest advances in improving mRNA vaccine stability， including rational mRNA engineering design， optimization of delivery platforms， development of novel stabilizing excipients， and improvements in manufacturing and preservation technologies， this review aims to provide new insights for the long-term stability research and industrial development of mRNA vaccines.