In recent years, urgent unmet medical needs due to the COVID-19 pandemic have accelerated the application of mRNA technology in vaccine development, leading to some of the first approvals of mRNA vaccines in human history by regulatory agencies around the world. For market authorization, comprehensive chemistry, manufacturing and control (CMC) information is required to assure the safety and quality consistency of mRNA vaccines. Evaluating mRNA vaccines for new virus variants poses a challenge for regulators, given the rapid optimization and development based on prior platform knowledge to accelerate the development process, which is traditionally limited for biological products. Here we summarize the current regulatory considerations of CMC evaluation on mRNA vaccines based on the scientific knowledge available, which will be updated with the advance of mRNA biology and pharmaceutical science.