Thixotropy in clay, characterized by a reversible decrease in viscosity upon disturbance followed by gradual recovery, significantly influences the bearing capacity and stability of foundations in engineering structures. This study investigates the thixotropic properties and microstructural evolution of the Zhanjiang Formation structural clay. Analyses were conducted using unconfined compressive strength tests, SEM (scanning electron microscopy), and NMR (nuclear magnetic resonance), focusing on samples with varying initial moisture contents and curing ages. Results indicate that the thixotropic strength ratio (A_t) of the Zhanjiang Formation clay increases with curing age, characterized by three distinct phases: rapid increase indicating strong thixotropy, a slower growth rate suggesting weak thixotropy, and eventual stabilization where thixotropy diminishes. Microstructural observations reveal that the soil's particle bonds strengthen over time, and pore alignment becomes more orderly, evolving from a loosely flocculated structure to a more homogeneous and compact honeycomb-like configuration. Furthermore, through gray relational analysis of the microstructural parameters extracted from SEM images and thixotropic intensity ratio, it can be concluded that: fractal dimension, probability entropy, and flatness, with probability entropy showing the highest correlation. This suggests that probability entropy is most indicative of thixotropic behavior, followed by fractal dimension and flatness.