Abstract: Separation of different grain size of aeolian silty soil is the basis of geotechnical test. At present, particle grading test can be divided into two types, dry and wet classification, and centrifugation and hydrostatic sedimentation are often used in the wet classification method. In order to find an effective way for the separation of silty soil, standard sieve method, filtration method, hydrostatic sedimentation method and the centrifugation method were conducted and compared, the separated soil particles were observed by microscopy and laser particle size analyzer. The rationality of each method is summarized and it is concluded that the standard sieve method is not suitable for silty soil as it could not separate small particle effectively. The filter method, centrifugation method and hydrostatic sedimentation method were compared aiming to the fine grain size of less than 0.075mm. The results show that filter method doesn't have ideal classification effect. Although the centrifugation method has the irreplaceable advantages in time control and experimental efficiency, the hydrostatic sedimentation method is more accurate in terms of classification results.