A data transmission method for use with a wireless mouse includes the following steps. Firstly, a mouse displacement data including a horizontal displacement and a vertical displacement is periodically transmitted from a wireless signal emitter to a wireless signal receiver in every wireless transmission time interval T1. Then, the horizontal displacement and the vertical displacement of the mouse displacement data are partitioned to acquire plural horizontal sub-displacements and plural vertical sub-displacements, respectively. Afterwards, one of the plural horizontal sub-displacements and one of the plural vertical sub-displacements are periodically transmitted from the wireless signal receiver to the computer system in every wired transmission time interval T2. By the data transmission method, the wired report rate is increased without largely increasing power consumption, and the moving trajectory of the wireless becomes smoother.