In order to increase the isoflavone content in fermented soya beans and improve the antitumor properties,soya beans were fermented by protease-producing strains Bacillus subtili D2 and β-glucosidase producing strain Bacillus subtili U35 through single and multi-strain fermentation.The contents of isoflavone were measured by HPLC.The relationship between isoflavone content and the antitumor properties was also analyzed.LLC cells were cultured to logarithmic growth time,and the isoflavone with different concentrations were added into the media.After the culture of 24h,48h,72h and 96h,the inhibiting rates of isoflavone to LLC cells were measured by MTT method.The morphological changes of the LLC cells were observed by fluorescence microscope.The results showed that isoflavone aglycones content of D2U35 multi-strain fermented soya beans were enhanced greatly,with 2.38 times(101.95 μg/mL) and 1.25 times(35.48 μg/mL) higher than that of D2 and U35 fermented soya beans,respectively.D2U35 fermented soya beans could also inhibit LLC cells,with 15.79% and 7.02% higher than that of D2 and U35 feimented soya beans,respectively.The multi-strain fermentation D2U35 not only improved the isoflavone aglycones content,but also improved the antitumor properties.The inhibition capacity of Isoflavone aglycones to LLC cells was higher than those of total isoflavones content and glycoside isoflavone.