A data transmission method and an apparatus are provided. In embodiments of this disclosure, a communication interface of a first electronic device is at least configured to send to-be-sent data packets of M data streams, and M is an integer greater than or equal to 1. A first data stream is one of the M data streams, a size of a to-be-sent data packet of the first data stream is a first target value, the first target value is associated with a target bandwidth of the first data stream, and the target bandwidth is less than or equal to a bandwidth of the communication interface. The communication interface sends the M data streams, and a size of a to-be-sent data packet of each data stream is a fixed value. For example, the size of the to-be-sent data packet of the first data stream is the first target value.