To evaluate the water conservation function of ecological system in Mount Tumor Nature Reserve, we selected the upstream of the Tailan River as the study area to quantitatively analyze the water conservation capacities of typical Picea schrenkiana forest, shrub woodland and grassland by using the combined method of field observation and laboratory experiments. The water conservation capacities in three layers including the forest canopy, litter layer and the soil layer, as well as the comprehensive capacity were analyzed. The result showed that the canopy interception capacity of Picea schrenkiana forest was greater than that of the shrub woodland in the study area, and the average throughfall and canopy interception were both greater than those of the shrub woodland. The average thickness of undecomposed layer was higher than that of semi decomposed layer in all kinds of vegetation, and the thickness and volume of litter layer in Picea schrenkiana forest were significantly greater than those in the shrub woodland. In all three types of vegetation, the natural and maximum water holding capacities of the semi decomposed layers were all higher than those of the undecomposed layers, and the natural and maximum water holding capacities of litter layer in Picea schrenkiana forest were both higher than those in the shrub woodland. The modified interception amounts of undecomposed layer were higher than those of semi decomposed layer in Picea schrenkiana forest and the shrub woodland. The average soil bulk density of different vegetation types followed the order of grassland > shrub woodland > Picea schrenkiana forest, while the order of soil porosity mean value was opposite; the natural moisture content, saturated water content and non-capillary water holding capacity of different vegetation types followed the order of Picea schrenkiana forest > shrub woodland > grassland, but the water storage capacity of soil layer deeper than 30 cm varied among different vegetation types. The water conservation capacities of different vegetation types were 181.06 ~ 237.63 mm, and the comprehensive and effective water conservation capacities both listed in the order of Picea schrenkiana forest > shrub > grassland. The soil layer contributed greatest in water conservation, and the total effective storage capacity was far less than the total water. In summary, Picea schrenkiana forest and shrub woodland in the study area had better water conservation ability. Grazing intensity and human disturbance were the important factors that affected the water conservation function of different vegetation types in the study area, especially for vulnerable grassland.