Abstract: The strains with pathogenicity of Ralstonia solanacearum isolated from sweet potatoes were grown in PYG medium at 28-30℃ for 48-72 hours After sterile centrifugation (2000 r/min ),the culture fluids were filtered through 0 45 μm Millipore filters The crude toxins (metabolite) were obtained The crude toxins of Ralstonia solanacearum in sweet potatoes is sensitive to thermal treatment and it’s biological activity decreased separately 0%、28 7%、100% at 50℃、 70℃ and 100℃ waterbath for one hour The crude toxins is not sensitive to ultraviolet ray and the biological activity is unchanged under ultraviolet light for 30min、60min and 120min The crude toxins is sensitive to Pronase and lysozyme,the biological activity was destroyed and the toxicity was lost while adding papayain (4-16 u/ml) or trypsin (4-16 u/ml) to the crude toxins It’s biological activity decreased 91 6%-92 0% while adding lysozyme(15000-60000 u/ml) to the crude toxins.