This paper aims to analyze the requirements of a file system for IoT electric meters, specifically focusing on the smart IoT electricity meters used by State Grid Corporation of China. Firstly, the characteristics of IoT electric meters and their file system requirements are analyzed. Secondly, a file system framework and interface are designed for the operating system of IoT electric meters. Next, popular file system types and their features are researched, and a comparison is made between littlefs and FATFS for porting onto the system. The experimental results show that the littlefs can achieve higher reliability and faster read-write speed, being more suitable for the application scenarios. Finally, this paper looks forward to the future trends of file systems for IoT electric meters.