A system on chip is integrated in a first semiconductor chip, and includes a secure element and at least one central processing unit that is coupled to the secure element. Security isolation exists between the secure element and the at least one central processing unit. The at least one central processing unit is configured to communicate with the secure element. The secure element includes a secure processor and a first memory that is coupled to the secure processor. The secure processor can suspend running first secure operating system software and further start second secure operating system software, to implement switching between multiple pieces of secure operating system software. Running data of running secure operating system software is stored in the first memory, and running data of secure operating system software that is not run is stored in a second memory outside the system on chip.