[Aim] The formation of the dispersal larva plays an important role in the transmission and spreading of pinewood nematode (Bursaphelenchus xylophilus) which is a major alien invasive pests of forest worldwide. However, its mechanism about formation and maintenance remains unclear.[Method] In this study, digital gene expression (DGE) libraries of two dispersal larvae[3rd instar (L_Ⅲ), and 4th instar (L_Ⅳ)] and of the propagative larva (L_n) were constructed to analyze the differences of gene expression of different developmental stages from aspects of maintenance of diapause, chemoreception and metabolic pathways.[Result] A total of 11184, 8533, 10781 genes were found for L_Ⅲ, L_Ⅳ and L_n according to reference genome, respectively. Compared with L_n, most of the genes in L_Ⅳ were down-regulated, and some genes, including chemoreceptor genes, nuclear hormone receptors and other metabolism related genes were up-regulated. The probable function of these genes is in regulating diapause stages, chemosensation and vector/host interaction in the dispersing larva. Gene ontology and pathway clustering analysis showed that most metabolic pathway in L_Ⅳ were down-regulated. However, genes related to metabolic pathways in L_Ⅲ expressed vigorously.[Conclusion] This results are consistent with phenotype of the physiological status of L_Ⅳ, which does not feed and has low level of overall metabolism.