Abstract: Thixotropy is a very important and unique property of soft clay in engineering. It is described as an isothermal,reversible,time-dependent process occurring under conditions of constant composition and volume,whereby a material stiffens while at rest and softened or liquefied upon remoulding. In this study,the thixotropic strength recovery of representative deep-sea soft clays collected in different areas in South China Sea is investigated with fall cone method. In addition,the microstructural evolution during thixotropy is captured by scanning electron microscopy,and the related microscopic characteristics are quantitatively analysed. The results present that all the deep-sea soft clays in South China Sea can show thixotropic behaviour. However,the thixotropic potential of different clays is quite distinguished,which might be related to the basic properties. The microstructure of clay during thixotropy changes significantly,and can transfer from dispersive to flocculation. The diameter and orientation characteristics of microstructural unit have some adjustment. The proportions of microstructural unit in small-sized parts decrease while the proportions in larger-sized parts increase with time. However,there is no obvious orientation of the arrangement of microstructural unit during thixotropy.