The invention relates to an MP3 compressed domain audio self-adaptation noise reduction method. The method is directly used for noise reduction on MP3 compressed domain. Firstly, MDCT coefficient is extracted from MP3 audio data containing noise, and activity detection is carried out on MP3 audio based on MDCT spectrum energy characteristic, so as to distinguish active audio band and mute band. Meanwhile a normal inverse Gaussian (NIG) distribution function is adopted to carry out prior statistic modelling on the MDCT coefficient according to the sparse property of the MDCT coefficient after MDCT coefficient is extracted form MP3 compressed audio data. Then a maximum posterior probability estimator based on NIG prior probability model is designed according to Bayesian theory, so as to obtain corresponding audio band attenuation factor. In the attenuation noise part, the attenuation factor is utilized to attenuate noise of the audio band, and attenuation iteration number is adaptively adjusted according to the attenuation weight of mute band audio, so as to realize noise reduction. Experiment result shows that noise in MP3 audio can be effectively eliminated by adopting the noise reduction algorithm of the invention, signal to noise ratio of compressed audio is improved, and MP3 audio after noise reduction has good quality.