Abstract: This study aims to explore the microdroplet motion patterns driven by the modulated surface acoustic wave (SAW). The directional drive of microdroplets is realized by exciting SAW with the sinusoidal signal modulated by a rectangular wave, and the droplet motion velocities are obtained by capturing and analyzing the droplet's motion images. A comparison of droplet motion driven by modulated SAW and continuous SAW is conducted, and the advantages of modulated SAW drive are revealed in terms of higher driving efficiency and smaller shape deformation. The motion velocities of the droplets with different volumes under modulated SAW driving are measured, and the result indicates that droplets with the volumes from 3 to 4 µL exhibit faster driven velocities due to their optimal acoustic energy absorption capacity. Furthermore, the relationships of droplet motion velocity with the modulation frequency and duty cycle of SAW driving are measured, and the underlying motion mechanism of the droplets is elucidated by combining numerical simulations. It is demonstrated that the driven velocity of droplets is influenced by the matching relationships of the droplet's shape deformation and recovery time with the frequency and duty cycle of the modulation signal. The highest driven velocity is achieved at the volume of 3.5 µL with the modulation frequency of 40 Hz and the duty cycle of 70%. By modulating the SAW exciting signal, the relatively stable droplet morphology can be kept while driving the droplets efficiently. In the microfluidic system involving droplets, shape preservation is critical for droplet transportation and subsequent processing. Therefore, the modulated SAW driving method of droplets holds great promise for a wide range of applications.