Abstract: The experiment applied national standard forest analysis method to study of hydrological effect of Pinus tabulaeformis,Platyclodus orientalis and Hippophae rhamnoides mixed plantation.The results showed that annual mean precipitation inside the mixed plantation was 20.1% lower than that ouside the mixed plantation.Its seasonal varieties in summer,autume,spring and winter gradually decreased.In mixed plantation,the annual mean air temperature was 0.1℃ lower than it in pure plantation and annual mean relative humidity was 4.5% higher than that in pure plantation.In mixed plantation,the cut discharges of tree layers increased by 56.6% and shrub layers increased by 395.7%.The annual mean runoff on the ground and modulus of runoff were 105.8 L and 10.58 m3·km-2·a-1 inside the mixed plantation.But those in pure plantation were 1 349.05 L and 134.9 m3·km-2·a-1.The soil erosion modulus was 0.65 t·hm-2·a-1 inside the mixed plantation but in pure plantation was 9.2 t·hm-2·a-1.The litter extant amount increased by 200% and litter water-holding capacity was 3.1 times of its own weight,the soil volume weight and compactness reduced by 6.3% and 17.7%,the water content,porosity and air permeability of soil increased by 6.1 %,13.9% and 20.3%.The soil physical property was improved.In different soil layers the soil volume weight and compactness gradually increased from the upper fo the cower strata.The porosity and air permeability of soil was the best in topsoil but decreased downwards.In mixed plantation the soil porosities of non-capillary in bottom,middle and top soil layers increased by 113.3%,38.6% and 32.6%.The maximal water-holding content,the minimum water-holding content and capillary water-holding content in mixed plantation were respectively 11.0%,9.8% and 10.5% higher than those in pure plantation,36.0%,16.0% and 25.6% higher than those in wild land.The water total storage and water storage of 0～40 cm soil layer in mixed plantation were 12.4%,22.7% higher than those in pure plantation and wild land.