Abstract: Composite soil with deep mixed column is widely used in strengthening soft soil subgrade. However, there is still a lack of understanding the dynamic characteristics of composite soil with deep mixed column and evaluating unreasonably the long-term performance of composite soil with deep mixed column. Based on above, this study conducted a series of large-scale triaxial test to investigate the influence factors of static deviator stress, replacement ratio and incremental loading/unloading on the dynamic parameters of unit cell of deep mixed column-reinforced soft soil. The results show that with the increase of the static deviator stress, the dynamic elastic modulus increases, the damping ratio decreases, and the critical dynamic stress ratio decreases. With the increase of the area replacement ratio, the dynamic elastic modulus increases slightly and the damping ratio decreases slightly. The staged unloading can deteriorate the dynamic properties of the unit cell. The damping ratio is of strong volatility, and the variation coefficient of damping ratio is 2.8 to 7.0 times that of the dynamic elastic modulus. The dynamic elastic modulus of the unit cell of the composite soil is 2 to 6 times that of the soft soil, and the improvement factor increases with the increase of the static deviator stress.