Abstract: Abstract:Using the four different resistant strains of pepper to Leveillula taurica(Lev. )Arn, this paper studied the activity change of Phenylalanine ammonia-lyase（PAL） in the inoculated leaf tissue and its upper and lower leaf tissue. The results showed that the activities of PAL of non inoculated were similar among cultivars.The PAL activities were increased in four cultivars after been inoculated with Leveillula taurica and the increasing rate of the activities of PAL in the resistance cultivars was more than that in the susceptible ones in the second and third day after inoculated and the changes were positively correlated with the resistance. In addition, the PAL activities were increased in the leaf that are upper or lower than the inoculated leaf. It was concluded that induced resistance could produced in non inoculated leaf after inoculation.