The invention discloses a method for implementing a file system in an embedded system, which comprises the following steps of: establishing the file system consisting of a file information area and a file data area, wherein the file information area consists of a plurality of file information structures for describing each piece of file information respectively, and the file data area is used for storing files; initializing the file system; and establishing and maintaining the file information area by using a journal method, and when writing operation is performed on the files each time, after the files are written into the file data area, updating the records of the file information to the file information area. In the method, the file system is implemented, can modify the number of the files to be stored and total capacity according to configurations, has a power failure protection function, high file reading / writing operation efficiency and small code sizes, is less dependent on an operating system and convenient to port, and occupies fewer resources.