Pinus koraiensis Seib. et Zucc and Larix dahurica Turcs are the most important species in Northeast China. The fine particles, such as sawdust and flakes, of the two species are essential raw material for wood products. Previously Mäule reaction was used to identify the particles of hardwood and softwood. However, this method cannot tell the difference between species of hardwood or softwood. In a recent study infrared spectroscopy was used for this purpose. Samples used were from the two species mentioned. The distinctions of their chemical composition and structure are analyzed, and the differences between their spectrum discovered. It is found that there are characterized absorption peaks at 1640, 780, and 720 cm^-1 in the spectrum for larch. This means that the larch contains more benzene ring conjugation ketoyl than the pine and has arabinogalactan with branch structure.