Two hundreds and thirty bacteria were isolated from the leaf of the Pinus massoniana in the Zijinshan and were tested for their nematicidal activity. Eight strains which had nematicidal activity to Bursaphelenchus xylophilus were found. The bacterium JK-JS3 showed the highest nematicidal activity to B. xylophilus. The bacterium cuhure which was diluted 2 times,4 times and 10 times still showed high nematicidal activity to B. xylophilus. After the nematodes were treated with the cultures for 72 h, the lethal rate of the nematodes actained 100%. The nematicidal spectrum of the bacterium JK-JS3 was tested,too. The results showed that the bacterium JK-JS3 had nematicidal activity to all tested nematode strains which included B. xylophilus,B, mucronatus, Panagrellus redivivus,Radopholus similis, Rhabditis sp. and Aphelenchoides besseyi. It was also seen that the nematicidal activity of the bacterium JK-JS3 to different nematode strains was different. The nematicidal activity of the bacterium JK-JS3 to B. xylophilus and Rhabditis sp. was the highest, and the following were B. mucronatus, P. redivivus, R. similis and A. besseyi. The bacteria were classfied by the morphological character and Biolog automated bacterial identification system. It was the Gram-positive bacteria which had peritrichous flagellum and could produce endospore. The bacteria belonged to Bacillus amyloliquefaciens.