Abstract: Under cyclic loading,a slope can be easily deformed and damaged.The failure mode of each part of the slope is different.Based on the technology of numerical simulation,two slopes with different heights are established.And the particle motion at slope shoulders of the two slopes are analyzed under 10 Hz cyclic vertical compressive load and horizontal shear load,respectively.According to the relation between force and deformation,the potential failure mode of slope shoulder is reveal.The results show that: under cyclic vertical compressive loading and horizontal shear loading,the trail of slope shoulder' particle motion is oval shape.However,the loading pattern and slope height affect the trail of the particle motion.Under vertical compressive load,the particle at lower slope shoulder is experiencing vertical vibration seriously.So the lower slope shoulder is more easily to surfer tension cut-off.Reversely,the particle at lower slope shoulder is experiencing horizontal vibration significantly under horizontal shear load,which show the lower slope shoulder is more easily subject to shear failure.Comparing with the lower slope condition,the vertical and horizontal amplitude of vibration of the particle at the higher slope shoulder under both vertical and horizontal load are close to each other,which show the shoulder of higher slope will be tensile-shear complex failure.