At present,most of the fillers used for railway subgrade bed are well-graded fillers.There are few studies on cumulative plastic deformation characteristics and critical dynamic stress of aeolian sand as subgrade fillers under train load.But aeolian sand as subgrade filler has been used in desert railway construction.A series of dynamic triaxial tests of aeolian sand samples,considering the influence of confining pressure,dynamic stress amplitude,compaction coefficient and moisture content,were carried out to investigate the evolution laws of cumulative plastic deformation and its critical dynamic stress.The test results are drawn as follows.The cumulative plastic strain of aeolian sand increases with the increase of dynamic stress amplitude,and it decreases with the increase of compaction coefficient and confining pressure.Taking the optimal moisture content as the cut-off point,the cumulative plastic strain of aeolian sand decreases with the increase of moisture content,when the moisture content is lower than the optimal moisture content.The cumulative plastic strain of aeolian sand increases with the increase of moisture content,when the water content is higher than the optimal moisture content.The accumulative plastic strain curves can be classfied into three types:stable,critical and failure.Accordingly,the critical dynamic stress of aeolian sand filler was obtained.The critical dynamic stress of aeolian sand increases with the increase of confining pressure and compacting coefficient.The critical dynamic stress of aeolian sand under saturated moisture content is obviously smaller than that under natural moisture content and optimal moisture content.The relationship between critical dynamic stress and confining pressure could be well fitted by linear function.The empirical formula of critical dynamic stress taking confining pressure and moisture content into account are obtained.The applicability of aeolian sand as subgrade filler under different working conditions were determined by the critical dynamic stress formula.The test results provide experience and theoretical basis for the design,construction and operation of desert railway.