Using the APF-Ⅰtype and ZM-808 type trap developed by Fujian Agriculture and Forestry University to trap the adults of Monochamus alternatus, the law of their activities in Xinluo District of Longyan City, Fujian Province was found out, which provided the basis for the scientific implementation of Bursaphelenchus xylophilus prevention and control technology. The results showed that the adults of M. alternatus started to move in late March, which was the early stage. The activity peak period was from mid-May to mid-July, the activity final stage of M. alternatus was from late July to early November and there was no activity from mid-November to early March of the following year. A total of 824 adult beetles were collected throughout the year, including 701 females and 123 males, with a ratio of 1:0.18 males to females. The number of female adults was far more than that of males. To control of B. xylophilus, trapping and killing of M. alternatus should be carried out from late March to mid-late October. All dead trees of unknown reason found before the end March should be cleaned up. At the same time, the prevention and control of the adults of M. alternatus in the forest should be strengthened, and the hidden dangers of transmission should be completely eradicated.