Updated project metadata. Pine wilt disease is a worldwide dangerous pine disease. We used Masson pine (Pinus massoniana) clones, selected through traditional breeding and testing for 20 years, with high resistance to study the molecular mechanism of resistance to pine wood nematode (PWN, Bursaphelenchus xylophilus). A total of 3491 proteins were identified from seedling tissue, among which 2783 proteins contained quantitative information. Total 42 proteins were up-regulated and 96 proteins were down-regulated in resistant lines. Of them, function enrichment analysis found that significant differences in proteins with pectin esterase activity or peroxidase activity. Proteins participating in salicylic acid metabolism, antioxidant stress reaction, polysaccharide degradation, glucose acid ester sheath lipid biosynthesis, sugar glycosaminoglycans degradation pathway also changed significantly. PRM results showed that pectin acetyl esterase, carbonic anhydrase, peroxidase and chitinase were significantly down-regulated, while aspartic protease was significantly up-regulated, which was consistent with proteomic data.These results suggested that Masson pine could degrade nematode-related proteins by increasing protease to inhibit their infestation, and enhance the resistance of Masson pine to PWN by down-regulating the carbon metabolism to limit available carbon to PWN or to be involved in cell wall components or tissue softening. Most downregulated proteins seem to take back seats prior to pathogen attacks. The highly resistant Masson pine, very likely, has evolved multiple pathways, both the passive and active, to defense against PWN infestation.