A data transmission method, where the data transmission method includes acquiring, by a first terminal, an output signal of a sensor of the first terminal, where the output signal of the sensor of the first terminal is a signal generated when a first magnet of a second terminal triggers the sensor of the first terminal, determining, by the first terminal, the output signal of the sensor of the first terminal as a low-level output signal, establishing, by the first terminal, a communication link with the second terminal, and determining, by the first terminal according to the communication link established by the first terminal with the second terminal, to perform data transmission with the second terminal.