The invention relates to a preparation method of a compound microbiological 
feed additive for fattening pigs, and an application method of the compound microbiological 
feed additive for fattening pigs. The compound microbiological 
feed additive for fattening pigs includes four different kinds of compound microbiological 
flora powders: 45 percent of 
lactobacillus helveticus, 45 percent of 
lactobacillus fermenti, 5 percent of 
bacillus subtilis, and 5 percent of 
bacillus licheniformis. The application method of the compound microbiological feed additive for fattening pigs is as follows: the compound bacterium powders are added into feed by a ratio of 0.4 to 100, or added into drinking water by a ratio of 0.05 to 100. The preparation method of the compound microbiological feed additive for fattening pigs includes the following steps: through liquid 
fermentation and with soybeans serving as a 
fermentation raw material, the 
bacteria respectively achieve a logarithmic phase (pH4-5) through twice enlarged cultivations; bacterium powders with water contents no higher than 5 percent and 
bacterial counts no lower than 10<8> per 
gram are obtained through 
spray drying; the compound bacterium powders are finally obtained. The compound microbiological feed additive provided by the invention effectively prevents 
disease infection and spreading among fattening pigs, greatly improves the meat quality and the dressing percentage, reduces the application of 
antibiotics and chemical additives, saves feed and cultivating water, improves economic and 
social benefits, and is an ideal compound microbiological feed additive.