A method, implemented by a computer system comprising a trusted execution environment (TEE) and a rich execution environment (REE) includes creating, by the TEE, a plurality of sub-threads preparing to implement sub-functions of a trusted application (TA), for each sub-thread, triggering, by the TEE, the REE to generate a shadow thread, where running of the shadow thread will cause a core on which the shadow thread runs to enter the TEE, and scheduling the created sub-thread to the entered core for execution.