Abstract: Abstract: Three kinds of probiotics (Bacillus subtilis NHS1, Lactic acid bacteria NHS03 and Marine red yeast NHS05) were used to optimize the solid state fermentation of soybean meal process by orthogonal design method L9 (34) combined with the comprehensive weighted evaluation method. The effects of inoculum size (A), environmental temperature (B), water feed ratio (C) and fermentation strains (D) on the protein content, lactic acid content, reducing sugar content and some other indicators were detected. Taguchi design and analysis were carried out by using Minitab 17, and weighted data processing was conducted by using multi-index experimental formula method. The results as follows: 1) Based on the weighted analysis, the weight coefficient of neutral protease was the greatest, reaching 1.773, followed by reducing sugar (1.719), lactic acid (1.590) and crude fat (the lowest). The results showed that neutral protease, reducing sugar and lactic acid had great influence on the quality of fermented soybean meal. 2) The date of the processing groups were analyzed according to the indicators comprehensive score formula Pi=Σ(Fj×Dij)/ΣF, and T9 had the greaest overall score, followed by T1 group and T8 group. The results indicated that the comprehensive level of 8 selected indeices reached the highest in the fermentation process of soybean meal in the condition of T9 combination (A3B3C2D1). Therefore, T9 was chosen as the optimal fermentation process. 3) The order of the importance of fermentation parameters for soybean meal based on the mean response table was fermentation strains > water feed ratio > environmental temperature > inoculum size. Fermentation strains and the ratio of water to feed were the main impact factors (P<0.05), while the mean response table for collogation score of the orthogonal test were not significant affected by environmental temperature and inoculum size. Considering the resource saving and production practice, the inoculation quantity of probiotics should be less collection and the environmental temperature should be lower (30℃). Therefore, the fermentation process A3B3C2D1 was optimized to be A1B2C2D1 in the present study, that means: the inoculum size of probiotics was 1%, environmental temperature was 30℃, the ratio of material to water was 2:1, and the optimal combination of Bacillus subtilis (NHS1), Lactic acid bacteria (NHS03) and Marine red yeast (NHS05) was 1:1:1. 4) Minitab17 was used to predict the optimal process A1B2C2D1, and the predicted results showed that the mean value was 0.993 3, and it was higher than the comprehensive score of the combination of A3B3C2D1 (0.986 3). Through experimental verification, the output of each impact indicator was consistent with the expected results, and the comprehensive score is 0.992 0, which was consistent with the predicted results. Moreover, all the technical indexes of fermented soybean meal were superior to the industry standard. The content of antinutrient factors were reduced greatly in the present study, and the content of amino acid showed an increasing trendency. The optimized process is stable, reasonable and efficient based on the above results, and it can be recommended for the fermentation process of soybean meal.