To enhance the sensitivity in the low-frequency range, a slotted low-frequency high-sensitivity microelectromechanical systems (MEMS) acoustic sensor structure was designed based on scandium aluminum nitride (ScAlN) piezoelectric films. The influence of the number of slots on the resonant frequency and voltage output was analyzed. A MEMS acoustic receiver with a resonant frequency of 29.3 kHz was fabricated. The highest sensitivity measured within the frequency range of 20-30 kHz exceeded -60 dB, indicating that the slotted structure proposed in this paper could achieve high sensitivity in the low-frequency range.