Abstract: To study the dynamic characteristics of improved expansive soil under cyclic loading, we used the dynamic triaxial apparatus to investigate the influence of confining pressure, dynamic stress level, loading frequency and loading mode on the cumulative plastic strain, stress-strain hysteretic curve and dynamic modulus of improved expansive soil.The experimental results indicated that the cumulative plastic strain increased with the increase of dynamic stress level, and decreased with the increase of confining pressure or loading frequency.As the dynamic stress level increased, the cumulative plastic strain state of the improved expansive soil changed from stable to collapse.Areas of hysteretic curves decreased with the increase of the number of cycles, and the hysteresis curve tilted closed to the stress axis, resulting in the hardening phenomenon.The dynamic modulus increased with the increase of dynamic strain.The dynamic modulus corresponding to the same dynamic strain was positively correlated with confining pressure, dynamic stress level, and loading frequency.Compared to single-stage loading, the multi-stage loading played an active role in improving the ability of the specimens to resist permanent deformation.According to the research results, confining pressure, dynamic stress level, loading frequency, and loading mode have a significant impact on the dynamic characteristics of improved expansive soil.The research results have reference values for understanding and evaluating the dynamic characteristics of improved expansive soil.