The invention relates to a metalized film capacitor self-healing discharge testing system and a metalized film capacitor self-healing discharge testing method based on sound pressure intensity. The metalized film capacitor self-healing discharge testing system comprises a soundproof box, a sound pressure microphone sensor, an insulating table, a signal switching box, a data acquisition card and aPC, wherein the insulating table is arranged at the bottom part of the soundproof box, a capacitor to be tested is placed on the insulating table, electrode bars are mounted above and below the soundproof box, the electrode bars are connected with a DC power supply, the capacitor is connected with the electrode bars by means of lead wires, the sound pressure microphone sensor is installed on the inner wall of a box body of the soundproof box, the sound pressure microphone sensor is connected with the signal switching box, the signal switching box is connected with the data acquisition card, and the data acquisition card is installed on the PC. The metalized film capacitor self-healing discharge testing system has test circuits which are simple, convenient and easy to build, and can monitorthe sound pressure waveforms in real time, capture and save self-healing pulse signals, play back the waveforms, perform filtering analysis and count the number of self-healing times.