To control Monochamus alternatus and its amount of population is one of the effective ways on controlling Bursaphelechus xylophilus.The Japanese black pine which were badly harmed by M.alternatus were sprayed with the ditution from diluting fenitrothion · buprofezen 50%EC with water to 100 times, 200 times and 300 times. In this trial, the treatment is divided into two groups: one is of the different concentration but the same object (trees in the forest), the other is of the same concentration but different environmental condition (trees in the forest and felling trees indoor). Each treatment repeated five times. In the meantime, the check is not treated. After twice trial, the result indicated that the mortality rate of M. alternatus is 71 33%, 52 31% and 37 82% in the condition that trees in the forest were sprayed with the 100 times, 200 times and 300 times fenitrothion·buprofezen, and 69 69% in the condition that the felling trees indoor were spraded with 100 times fenitrothion·buprofezen, but the mortality rate of the check is only 8 92%. By this trial, it was also found that the dead adults of M.alternatus laid in the entrance of emergance hole, so enhancing the somatic character of fenitrothion · buprofezen can enhance the injury ratio of larva and pupae of M.alternatus. To control Monochamus alternatus and its amount of population is one of the effective ways on controlling Bursaphelechus xylophilus. The Japanese black pine which were badly harmed by M.alternatus were sprayed with the ditution from diluting fenitrothion · buprofezen 50% EC with water to 100 times , 200 times and 300 times. In this trial, the treatment is divided into two groups: one is the different concentration but the same object (trees in the forest), the other is the same concentration but different environmental conditions (trees in the forest and felling trees indoor. Each time after five trials, the results indicate that the mortality rate of M. alternatus is 71 33%, 52 31% and 37 82 % of the condition that trees in the forest were sprayed with the 100 times, 200 times and 300 times fenitrothion · buprofezen, and 69 69% in the condition that the felling trees indoor were spraded with 100 times fen itrothion · buprofezen, but the mortality rate of the check is only 8 92%. By this trial, it was also found that the dead adults of M.alternatus laid in the entrance of emergance hole, so enhance the somatic character of fenitrothion · buprofezen can enhance the injury ratio of larva and pupae of M.alternatus.