Abstract: Experimental study on the overconsolidated clay under the cyclic principal stress rotation(CPSR) was performed.Emphasis was put on the influence of different overconsolidation conditions on the characteristics of samples during CPSR.It was found that with the increase of the over consolidation ratio,the equivalent dynamic stiffness and dynamic strength of samples during CPSR increased obviously,while these characteristics were independent of the back pressure control condition during overconsolidation.But whether or not the back pressure was kept constant greatly influenced the generation and level of development of negative pore pressure during the following CPSR stage.