Abstract: The antagonistic effects of bacterial strains in complex microbial inoculants and their culture condition were studied by Oxford cup method and liquid fermentation， respectively. The results showed that there were obvious antagonistic effects between different strains， but the antagonism between the strains could be reduced to a minimum by adjusting the ratio. The minimum proportion about antagonistic effect of strains was Lactobacillus acidophilus∶Saccharomyces cerevisiae∶Bacillus subtilis∶Bacillus licheniformis∶Paenibacillus mucilaginosus∶Bacillus cereus∶Bacillus amyloliquefaciens∶Aspergillus niger∶Aspergillus oryzae∶Streptomyces microflavus=6∶3∶2∶2∶6∶2∶2∶3∶2∶2; The first medium composition was selected as the optimal culture medium， pH value was 6.5. Finally， the adding order of these strains was determined according the habits， growing environment and fast live bacteria counting results， the adding order was: Lactobacillus acidophilus → Saccharomyces cerevisiae → Bacillus subtilis → Bacillus licheniformis → Paenibacillus mucilaginosus → Bacillus cereus → Bacillus amyloliquefaciens → Streptomyces microflavus → Aspergillus niger → Aspergillus oryzae.

Key words: complex microbial inoculants, antagonistic effect, strain ratio, culture condition