Abstract: Different concentrations of EM inoculants were applied in the test red soil using pots experiment.The purpose of this study was to investigate the effects of EM inoculants to soil characteristics and peanuts biomass.The results showed that the soil bulk density decreased with the increase of EM inoculants concentrations, and the soil moisture content increased with the increase of EM inoculants concentrations.The acidity of red soil was alleviated by using EM inoculants, and the pH value increased with the increase of EM inoculants concentrations.Soil organic matter, total nitrogen, total phosphorus, alkali-free nitrogen, and effective phosphorus content were increased first and then decreased with the increase of EM inoculants concentrations, were 6.49 times, 2.11 times, 2.21 times, 3.07 times and 5.05 times than CK, respectively and reached the maximum when the concentration was 70%, the content of organic matter, total nitrogen, total phosphorus, alkali-nitrogen and effective phosphorus.The increase of pot peanut biomass was 19.56%-84.78%, which was higher than CK significantly.The biomass was highest at 70% concentration.70% concentration of EM inoculants can be used in the planting of peanut crops in red soil area in southwest of China.