Abstract: Pine wilt disease was complex infection caused by pine wood nematode (Bursaphelenchus xylophilus), and bacteria. Studying the relationship between B. xylophilus and bacteria may provide evidence for the pathogenic mechanism of pine wilt disease. To clarify the relationship, the bacterial strains were inoculated to marinade on different aseptic B. xylophilus surface body surface,and cultured aseptic B. xylophilus after added the bacteria was to the B. xylophilus suspension. The results showed that the reproduction of bacteria was stimulated by the marinade of B. xylophilus body surface, B. xylophilus numbers increased more rapidly with bacteria present than without bacteria. This revealed that the reproduction and growth of B. xylophilus was also promoted by the bacteria. In conclusion, B. xylophilus and the bacteria benefited each other. Experiments were also designed to investigate the tropism test of aseptic B. xylophilus and bacteria, and test the specificity between the B. xylophilus and bacteria it carried. The results indicated that the bacterial strain of P. agglomerans or the bacterial strain mixed with P. agglomerans had obvious taxis towards all isolates of aseptic B. xylophilus. Experiments also tested the specificity between the B. xylophilus and bacteria it carried. The results showed that the aseptic B. xylophilus has no taxis towards the bacteria it carried, and that there was no obvious specificity taxis to the B. xylophilus with the bacterial strains it carried.