Abstract: The bioassay method of virulent Ralstonia solanacearum strain was established on the tomato plants treated by different concentration of virulent R. solanacearum strain FJAT-91. The results showed that the R. solanacearum strains isolated from wilted tomato plants were virulent strains according to the colony form and test of polymerase chain reaction (PCR) with special primers. The disease symptom of tomato plants treated with different concentrations appeared on the fifth day. The tomato plants began wilting on the fourth day, which were treated with concentration of 104 cfumL-1, and the incidence was reached 90% after 8 days. Time to LC50 of tomato plants was shortened along with the increasing of concentration of R.solanacearum. Therefore, the concentration of 104 cfumL-1 is the optimal one that could shorten test period and make the tomato plant wilt.