Abstract: This paper aims at studying the microbial fermentation effect of two different bacterial inoculants, Bacillus subtilis and beer yeast, respectively, which were vaccinated on apple residue, then analying and comparing related influential conditions for mixed strains fermentation. Their true protein content in fermented materials were calculated through three factors orthogonal test level （size ratio, inoculation quantity, pH）.The results showed that the true protein content of mixed strains of Bacillus subtilis and beer yeast could reach up to 13.58%, and the biggest influenced factor was size ratio, followed by pH, recommending to fermentation parameters of size ratio at 1.0∶1, inoculation quantity of Bacillus subtilis with 3%, pH 5.The content of true protein may be further improved if yeast and bacteria agent was synergic at fermented apple residue.

Key words: apple residue; fermentation; feed protein