A secure data transmission apparatus includes: a dedicated communication signal processor, configured to send a first security interrupt to an application processor; and the application processor, configured to execute rich execution environment (REE) software, execute trusted execution environment (TEE) software under a trigger of the first security interrupt, and obtain first information from a shared memory of the dedicated communication signal processor and the application processor based on the first security interrupt. The dedicated communication signal processor is further configured to receive a second security interrupt sent by the application processor, and obtain second information from the shared memory. The application processor is further configured to send the second security interrupt to the dedicated communication signal processor.