A computer-implemented method, non-transitory, computer-readable medium, and computer-implemented system are provided for data transmission in a trusted execution environment (TEE) system. The method is executed by a first thread in multiple threads on a TEE side. The method includes obtaining first data; obtaining a TEE side thread lock; calling a predetermined function by using the first data as an input parameter to switch to a non-TEE side; obtaining a write offset address and a read offset address respectively by reading a first address and a second address; determining whether a quantity of bytes of the first data is less than or equal to a quantity of writable bytes; if so, writing the first data into third addresses starting from the write offset address; updating the write offset address in the first address; returning to the TEE side; and releasing the TEE side thread lock.