The invention discloses a broadband micro-perforated board sound absorber, a sound absorber performance prediction method and a sound absorber structure design method. The sound absorber comprises a surface micro-perforated board and a back chamber with unequal periodicity depth, and the back chamber is used for expanding sound absorption bandwidth of the sound absorber. The performance prediction method is used for predicting a sound absorption coefficient frequency spectrum of the sound absorber, through finite element simulation and experiment measurement verification, the performance prediction method is accurate and reliable; the structure design method used for effectively realizing the broadband micro-perforated board sound absorber comprises steps that (1), a depth matrix of the periodic back chamber is designed on the basis of the secondary residual sequence combination arrangement theory; and (2), evaluation is realized on the basis of the performance prediction method, combination of parameters of the sound absorber are sequentially determined, including total sound absorber width of the periodic back chamber, depth of each sub back chamber, board thickness of the micro-perforated board, aperture and perforated percentage. Through the sound absorber performance prediction method and the sound absorber structure design method, the micro-perforated board sound absorber having the broadband sound absorption performance can be accurately, reliably and simply designed.