The rotting of municipal solid waste is one hazard in the RDF production process, In this study, the effect of CaO addition on rotting prevention is experimentally examined, A mixture of soybean protein and distilled water was used as the model refuse. Escherichia coli was adopted as a rotting indicator. CaO powder was uniformly added to the model refuse, and the changes of DH and cell number were measured, The rotting was prevented by CaO addition because CaO addition made the alkalinity in the sample higher, The effect of CaO addition on rotting prevention depends on moisture content.