Abstract: Heartwood, sapwood and bark of olga hay larch (Larix olgensis var. changpaiensis) were used as raw material to obtain extractives by extracting with C2H5OC2H5,CHCl3, (CH3)2CO, MeOH and H2O,respectively. Antibacterial activities of these extractives against Coriolus versicolor and Gloeophyllum trabeumr were investigated by filter paper method. It was found that MeOH extractives and (CH3)2CO extractives of heartwood have better inhibition effect against C. versicolor; H2O extractives of bark has better inhibition effect both against C. versicolor and G. trabeum. Wood preservation activities of these two kinds of extractives were also studied in lab, the growths of wood-inhabiting fungi in samples were observed by scanning electron microscope (SEM). The effect was compared with typical wood preservative acid-copper-chromate (ACC), the result showed that MeOH extractives of heartwood has better decay-resistance against C. versicolor, H2O extractives of bark has decay resistance against G. trabeum.