Abstract: In order to study the effect of traffic loading induced static deviator stress on the undrained cyclic properties of saturated soft clay,an undrained cyclic triaxial test was designed.The cyclic loading was simplified as sine wave plus static deviator stress.And the effect of static deviator stress on deformation,pore pressure and cyclic strength of soft clay was studied.It was found that the static deviator stress greatly affected the cyclic properties of soft clay.The development of plastic deformation and residual pore pressure was accelerated,the cyclic strength curve lowered and the minimum limited cyclic strength was reduced.And its effect increased with the increasing of static deviator stress.It was shown that saturated soft clay was easier to fail under traffic loading induced dynamic stress.