Abstract: The different types of larch natural forests in Da Hinggan Mountains were taken as the research object. 11 eva1uation indexes were determined from forest canopy layer, litter layer, soil layer and productive forces etc, and weight of evaluation were carried out by the analytic hierarchy process and principal component analysis method to evaluate the differences of water conservation function of the different types of larch natural forests, and aimed at the reasonable management of the larch natural forests and improved water conservation function of larch forests provide a strong basis. The results showed that the Rhododendron-Larix had better water conservation function, the Larix pure the next, Birch-larix the worst. Focus on the protection of the Rhododendron-Larix should be taken in the Da Hinggan Mountains region, in order to increase the water conservation function of the drainage basin.