In order to quantitatively evaluate the soil characteristics and water conservation function of different forests in the alpine mountainous areas of Datong County of Qinghai Province and to provide a theoretical basis for reasonable spatial allocation of forests, immersion method, cutting ring method, fixed head method and sulfuric acid potassium dichromate method were used to determine litter properties, soil porosity, soil permeability and soil nutrient status of the 0-40 cm soil layers of five kinds of forest. The results showed that there were significant differences in soil properties and water conservation function among forest types. (1) The litter size and the maximum water holding capacity of the litter in the five forest types were in the order of Picea crassifolia-Betula platyphylla > P. crassifolia-Larix principis-rupprechtill > P. crassifolia forest > L. principis-rupprechtii forest > Betula platyphylla forest. (2) In the 0-40 cm soil layer, the average soil organic matter content was in the order of P. crassifolia –L. principis-rupprechtill > P. crassifolia-B. platyphylla > B. platyphylla forest > P. crassifolia forest > L. principis-rupprechtii forest. (3) In the 0-40 cm soil layer, soil bulk density of five kinds of forest types increased with the increment of soil depth, and followed the order of B. platyphylla forest > L. principis-rupprechtii forest > P. crassifolia-B. platyphylla > P. crassifolia forest > P. crassifolia-L. principis-rupprechtill. (4) In the 0-40 cm soil layer, total porosity of the soil under five forest types decreased with the increment of soil depth. The mean value of soil total porosity was in the order of P. crassifolia-L. principis-rupprechtill > P. crassifolia forest > P. crassifolia-B. platyphylla > L. principis-rupprechtii forest > B. platyphylla forest. (5) In the 0-40 cm soil layer, soil average infiltration rate of the five types of forests was in the order of B. platyphylla forest > P. crassifolia-B. platyphylla > P. crassifolia-L. principis-rupprechtill > L. principis-rupprechtii forest > P. crassifolia forest. (6) Based on the total water-holding capacity of litter and soil, water conservation function of the five types of forests followed the order of P. crassifolia-L. principis-rupprechtill (4 427.40 t/hm2) > P. crassifolia forest (4 365.33 t/hm2) > P. crassifolia-B. platyphylla (4 055.04 t/hm2) > L. principis-rupprechtii forest (3 729.64 t/hm2) > B. platyphylla forest (2 650.31 t/hm2).