Abstract: To explore the relationship between dynamic changes of superoxide anion (O-·2) in the pine trees infected by Bursaphelenchus xylophilus and the host tissue lesions, O-·2, superoxide dismutase (SOD) and physiological changes in the interaction between Pinus taeda，P. massoniana，P. thunbergii and Bursaphelenchus xylophilus were studied. The results showed that growth rate of O-·2 content and value of SOD activity in three kinds of pine trees was P. taeda＞ P. massoniana＞P.thunbergii. At the early stage of inoculation (after 4 hours of inoculation), it increased fast in the resistant pines. The damage of resistant pines was lighter than that of the susceptible pines; At the late stage of inoculation (after inoculation 72 h to 120 h hours),the content of O-·2 and value of SOD activity in three pines was P. taeda＞ P. massoniana＞P.thunbergii，the development of physiological changes of P. taeda was slower than that of P.thunbergii and P. massoniana (P. massoniana slower than P.thunbergii),and the damage of that of P. taeda was lighter than P.thunbergii and P. massoniana. This indicated that the changes of O-·2 and SOD activity of in different resistance pines infected by Bursaphelenchus xylophilus were closely related to the host tissue lesions, superoxide may be important signal substances which mediated the resistant signal transduction in pines infected by Bursaphelenchus xylophilus.