Abstract: Monochamus alternatus is widely distributed. Standard investigation and trace investigation methods were used to investigated the damage situation of Monochamus alternatus in Guangyuan city. Altitude, forest composition and other related indicators were surveyed simultaneously. The danger degree of Monochamus alternatus was evaluated. The results showed that: (1) The damage degree of Monochamus alternatus in this area was closely related to tree species. The host tree species were mainly Pinus massoniana Lamb., Pinus tabuliformis Carrière and Pinus armandi; (2) The distribution of Bursaphelen-chus xylophilus was closely related to stand structure, altitude and stand factors, as well as human factors; (3) The damage degree of Monochamus alternatus in Guangyuan was moderate or lower in this area, and some areas was seriously damaged, and corresponding measures should be taken to prevent and control it.