The present invention provides a lightweight file system management method in a communication device, including a file storage process, a file retrieval process, and a file operation process. In the file storage process, file header information and file data are stored separately in a system storage device. The content of the file header information includes file mapping information, file size, file offset pointer, and space usage identifier, and the file system contains a file mapping information table; the file retrieval process includes performing segmented retrieval of the file header information according to the file name , and judge whether the file header information is used through the space use identifier; the file operation process includes obtaining the terminal file name, performing file retrieval on the file name, matching the file header information corresponding to the file name, and directly operating the physical storage address of the file data . The invention can directly read and write the physical address of the file data only by retrieving the header information of the file, reduces the file retrieval speed, and improves the file operation efficiency.