Since the sound absorption of micro perforated panel absorber (MPA) was bound up with structure parameters, so the effects of these parameters on the sound absorption of micro perforated panel absorber was investigated. The reliability of the theoretical results calculated by transfer matrix method was checked. The influence of the perforation rate, perforation diameter, plate thickness and cavity depth of MPA on acoustic characteristics was then discussed. The results indicated that the main factors influencing the resonant sound absorption were perforation rate, perforation diameter and plate thickness, and that the resonance frequency of MPA was determined by cavity depth. The resonant sound absorption decreased with the increase of the perforation rate, perforation diameter and plate thickness，and increased with the raising of cavity depth. The sound absorption curves moved to the low frequency zone and frequency bandwidth increased with the raising of perforation rate. However, when the perforation diameter and plate thickness and cavity depth of MPA increased, sound absorption curves moved to the high frequency zone and the frequency bandwidth decreased at the same time.