In this paper, a series of undrained dynamic cyclic triaxial tests were conducted to investigate structure effect on soil response due to cyclic loads. Soil samples used in this study are 1) undisturbed Shanghai marine clay and 2) artificially disturbed and remoulded Shanghai marine clay. Dynamic response, including strain development, effective stress path and pore water pressure, of both clay samples that subjected to cyclic loads were measured, respectively. Test results between undisturbed and remoulded disturbed samples were compared in detail to clarify the role that soil structure may have played during repeated loadings. It is found that the soil structure has significant influence on residual pore water pressure development. Based on the experimental results, a partition diagram is proposed to evaluate the accumulated pore water pressure of clay in different sensitivities when estimating liquefaction potential subjected to cyclic loads.