Seismic settlement is one of main earthquake disasters of ground base.So far some experiential formulas have been established to estimate the permanent strain of soil

but the number of parameters of these experiential formulas are too many.To determine these parameters

a lot of tests must be done.In this paper a series of seismic settlement tests of recently deposited muddy soil in Nanjing city were performed by WFI dynamic cyclic triaxial apparatus made in England.The permanent strain under different cell pressure

consolidation ratios and axial cyclic stress were acquired.It is found that the relationship of axial cyclic stress and number of cycles under different cell pressure and consolidation ratios could be normalized by shear stress ratio in the double logarithm reference frame based on the concept of maximum cyclic shear plane.That is all the parameters of seismic settlement can be determined by test under one cell pressure and consolidation ratio.The permanent strain formula established by Zhang Ke-xu and Chen Guo-xing could simulate the characteristics of seismic settlement of recently deposited muddy soil in Nanjing city.The permanent strain of the recently deposited muddy soil in Nanjing city increased suddenly when permanent strain is over 4%.