Abstract: Effects of salicylic acid (SA) on the induced resistance in Japanese black pine(Pinus thunbergii) seedlings to pine wilt disease and the changes of PAL and POD in the seedlings, during induced phase with SA were studied. The results showed that resistance of different degree induced by both spraying needles and soaking roots with SA and the SA could excite the increase of PAl. and POD. The better effects of induced resistance in pine seedlings by spraying needles were 61.9% when the concentration of SA was 0.01 retool/L, and that by soaking roots with 0.01 mmol/L SA was 71.4% when the soaking time was 3 h. The induced resistance in pine seedlings inoculated defiantly with Bursaphelenchus xylophilus was better at 5 days than at 10 days after the spraying and soaking treatments with SA. The induced resistance was better with soaking roots, which was better than spraying needles. The activity of PAL andPOD in the pine seedlings was increased and reached the highest level on the eighth day, POD 146% and PAL 64% respectively. Later, the enzyme activity decreased, but it was still higher than that of the control, POD 221% and PAL 150% on the twelfth day.