<p>This paper presents a fundamental study to investigate the stiffness parameters of kaolin clay with two controlled structures at a wide range of strains through resonant column and cyclic triaxial tests. Meanwhile, the cyclic responses of the two structural samples under three cyclic loading modes are also studied. Test results indicate that the dispersed sample exhibits a more robust structure and a higher maximum shear modulus, whereas the flocculated sample displays a weaker structure and is more sensitive to variations in confining pressure. Soil structure plays a more important role in the stiffness properties of small to intermediate strain (i.e., 10^–5–10^–2) than large strain (i.e., &gt; 10^–2). The normalized shear modulus and damping ratio of the two structural samples are identical and independent of plasticity index. Under the same cyclic stress amplitude, the flocculated samples produce more significant pore water pressure and exhibit greater contraction in all three series of cyclic triaxial tests. The generated axial strain of the flocculated sample approaches failure gradually, whereas it develops rapidly in the dispersed sample as it approaches failure. With more structure adjustment than the dispersed sample in the staged drained cyclic tests, the flocculated sample can withstand cyclic loading with a larger stress amplitude.</p>