The present application provides a secure element comprising a processor and a memory integrated into a semiconductor chip; the memory is configured to provide a storage space for the processor to load and run a secure program, the secure program includes an image of a secure operating system, and the image of the secure operating system includes a system image resident segment and a system image dynamic loading segment. The processor is configured to: divide the system image dynamic loading segment into a plurality of pages, where each of the plurality of pages includes some content of the system image dynamic loading segment; perform security processing on each of the plurality of pages; and migrate each security-processed page to an external storage of the secure element.