The soil physical characteristics on five types of degraded alpine grasslands in Maqu County in the Upper Yellow River were studied.Results showed that soil bulk density,porosity,moisture capacity,and water storage capacity in 0—30 cm soil layer of the five degraded grasslands were significantly different.Soil bulk density increased with the aggravation of degraded alpine grasslands and also increased with the increment of soil depth.The corresponding values ranged from 1.085 to 1.447 g/cm3 and 1.111 to 1.248 g/cm3,respectively.Soil total porosity,maximum moisture capacity,and total water storage capacity decreased with the aggravation of degraded grasslands,their range values were 46.214%~58.162%,26.765%~52.369%,and 1 386.420~1 744.872 t/hm2,respectively.The soil physical characteristics decreased with the increment of soil depth and the range values were 52.783%~57.285%,40.504%~50.057%,and 527.833 t/hm2~572.852 t/hm2,respectively.Soil permeability firstly decreased with the aggravation of degraded grasslands and then increased.By soil permeability,the order of grasslands was moderately degraded grasslandslightly degraded grasslandheavily degraded grasslandnon-degraded grasslandextremely degraded grassland.Study of infiltration process indicated that soil permeability of non-degraded grassland was good and its water conservation function was better than heavily degraded grassland.