Abstract: Density, saturation, and void ratio are fundamental physical properties of soil, while strain energy, strength, stress, and strain represent its mechanical characteristics. Factors such as confining pressure and loading rate significantly influence soil behavior. Based on the concept of shear strain energy, a structural parameter derived from shear strain energy was proposed. This parameter defines soil structure by integrating both physical and mechanical property parameters; the relevant expressions were derived and subsequently validated. The parameters in the expression were calibrated using laboratory test results, yielding a structural characterization model. Using the structural parameter expression, an incremental expression for structural degradation was derived, and the degradation process during wetting-loading was explored. The results show that in the initial state, the soil structure during triaxial shear exhibits an exponential relationship with saturation and an inverse relationship with density. The influence of saturation and porosity on loess structure (i.e., the slope of the ln E^*-S_r curve) is negligible under varying confining pressures and loading rates. The reference structure (the intercept of the ln E^*-S_r curve) increases with increasing confining pressure. During the loading and wetting process, the structural parameter decreases monotonically with increasing saturation and deformation until the soil is destroyed and the structure is completely degraded.