Abstract: 14 strains of entomogenous fungi were isolated from the Mechoris ursulus nymphae with pathological symptom, and these 14 strains of entomogenous fungi were employed in the virulence test against the M. ursulus nymphae. 2 of the strains, i.e., NO.6 and NO.7 with stronger infestation effect were screened out to conduct the concentration gradient test. The results showed that the median lethal time (LT50) of these two strains was 2204d and 2942d, and the median lethal concentration (LC50) of these two strains was 303×105 and 284×105 respectively.