The invention discloses a strain of bacillus coagulans (Bacillus coagulans) Daoduo 4 and a screening method thereof, and also discloses a microbial preparation containing the strain, a preparation method and an application of the microbial preparation. The microbial preparation of the present invention has simple cultivation, stable structure, non-toxic, harmless and no side effects, can effectively inhibit the reproduction and growth of spoilage bacteria, pathogenic bacteria and other harmful microorganisms, has strong stress resistance to the environment, has high temperature resistance, acid resistance, and Choline and other advantages can inhibit the growth of harmful bacteria in garbage, feces and sewage under complex conditions, eliminate odors, reduce pollution, and improve the environment. On the other hand, it can effectively remove volatile organic compounds (VOC), and it can be used in newly renovated houses and other places, which can significantly reduce the harm caused by decoration pollution to human health.