Shear failure of compacted loess in different frequencies is studied using a torsion shear apparatus and the effects of frequency on dynamic strength and dynamic strength parameter are investigated.(1) At a certain defined confining pressure

dynamic strength of compacted loess increased with the rise of the frequency

showing a poses tive relation with frequency.(2) At a certain defined frequency

dynamic strength of compacted loess increased with the rise of confining pressure.(3) Both dynamic cohesion and internal fraction angle of compacted loess are increased with the rise of frequency.(4) The dynamic cohesion and the internal fraction angle are decreased and tend to be steadv with the increased vibration.