Abstract: The virulence of pine wood nematode [Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle] from Japan and Nanjing China was tested on three-year-old Cedrus deodara and Pinus thunbergii. The results showed that the different source nematode all had a strong virulence on P. thunbergii, but had different effects on C. deodara. The nematode from Japan induced 70% C. deodara seedlings dead, the Chinese one had a light virulence. The number of nematode in P. thunbergii was larger than in C. deodara. The symptom of infected C. deodara by nematode was also described. This study was valuable to control pine wilt disease especially on C. deodara.