A new noise reduction algorithm based on acoustic scene classification is proposed. Three acoustic scenes of pure speech, noise, noisy speech are classified by modulation filter. The parameters of noise reduction algorithm are adjusted by the result of scene classification. Different attenuation coefficient is adopted according to the different acoustic scene. Satisfied experimental results are achieved in the digital hearing aid testing system. Better than 95% accuracy is acquired in acoustic scene classification experiment. In the environment of different kinds of noises input, the signal-noise ratio (SNR) and MOS score are increased apparently. The quality of output speech in digital hearing aids is improved effectively.