Abstract: Nanosecond pulse discharge has many advantages in sound production. For example, it owns wider frequency domain response and smaller components, and is suitable for some harsh surrounding environments, etc. In the field of nanosecond pulse air discharge, the researches on the relationship between electrical signal and acoustic signal and the principle of sound generation are rarely available in the literature. In this paper, an experimental platform for electrical and acoustic joint diagnosis was built. The electrical and acoustic signals were collected in real time under different pulse discharge energy and discharge gap distances, and the variation law of the peak sound pressure with different experimental parameters was summarized. The experimental results show that a single nanosecond pulse air discharge can produce pulse sound wave with microsecond pulse width. The amplitude of pulse sound pressure increases with the increase of pulse discharge energy and gap distance. The peak value of sound pressure increases by about 3 Pa for every 1mJ of pulse discharge energy, and about 20 Pa for every 1mm gap distance. Based on the experimental results, the wave equation of gas pressure in the process of sound generation is introduced, and a mechanism assumption of conversion from electricity to sound in nanosecond pulse discharge is proposed.