The toxicity bioassay of Verticillium lecanii （Zimm） KMZW-1 to Phenacoccus solenopsis Tinsley under five different concentrations ranged 3.0×104， 3.0×105， 3.0×106， 3.0×107， 3.0×108 spores/mL was studied in laboratory by topical application, when the 1st, 2nd and 3rd larvae and the female adults were vaccinated respectively. The results indicated that the virulence of V.lecanii KMZW-1 to P.solenopsis was high. The accumulative mortality gradually increased with the increase of the concentration, and is highest at the concentration of 3.0×108 spores/mL. The accumulative mortality of vaccinated female adults was higher than the vaccinated larvae. The highest median lethal concentration of 1st, 2nd and 3rd and adult in 9th day were 1.486 8×105, 3.661 7×103, 9.817 6×104, 2.796 0×104 spores/mL respectively, and the median lethal time were 5.21, 5.55, 5.44, 4.87 d respectively.