[Objective]The aim was to optimize the appropriate solid state fermentation (SSF) conditions.[Method] The Optimization of solid state fermentation using a mixture substrate of bean curd residue and the marc with Bacillus natto was developed.[Result]The best fermentation condition optimized by the test of single factor and the orthogonal design respectively was mixing ratio of bean curd residue to marc2:1, substrate pH value 6, fermentation temperature 39℃, inoculum volume 10/% and fermentation time 48h.Under this optimized fermentation condition, the content of crude fiber in the substrate decreased from 107.8mg/g before SSF to 56.2mg/g after SSF, and the degeneration rate of crude fiber was 47.87%[Conclusion]The bean curd residue in its palatability Was enormously improved by SSF with Bacillus natto strain, Which could be expected to be widely used as raw material of health foodstuff.