In order to study the improvement effect of polyacrylamide (PAM) on the flow state solidification soil, the effects of PAM dosage, liquid-solid ratio, and ash soil ratio on the widely distributed soft soil in the middle and lower reaches of the Yangtze River were studied. The results showed that PAM can quickly reduce the flowability of cement-based flow state solidification soil, improve viscosity, and slow down the early solidification speed of cement-based soil. The improvement effect of PAM on the flowability of fluidized solidification can be quantitatively described by net flow rate. It can be concluded that the net fluidity of fluid cement soil with different initial liquid-solid ratios decreases at the same level after adding a certain proportion of PAM. For soft soil with a liquid-solid ratio of 70% to 80%, it is recommended to control the PAM content at 0.02% to 0.03% to ensure that the flowability meets the backfill requirements and the on-site construction effect is better. At the same time, PAM effectively improves the freedom of the construction process. On this basis, the relationship between the dynamic shear force and fluidity of the soil was obtained, which can better fit the measured data.