Abstract: The urgent engineering and environmental challenge of efficiently processing large volumes of high-water-content sludge is addressed by transforming it into self-compacting flowable solidified soil, which serves as an effective resource utilization strategy. This study investigates the method of flocculation, filtration, and solidification in the laboratory preparation of self-compacting flowable solidified soil, analyzing the effects of the flocculation process, filtration process, admixture of solidifiers, and the addition of water-reducing agents on the fluidity and unconfined compressive strength of the solidified soil. Results indicate that the use of flocculants effectively reduces the flow value of the sludge and enhances the strength of the solidified soil. Filtration significantly accelerates the preparation of the self-compacting flowable solidified soil, achieving the desired fluidity within one hour and doubling the unconfined compressive strength compared with unfiltered samples. While the addition of cement significantly enhances the unconfined compressive strength of the solidified soil, it has a minimal impact on its fluidity. The optimal sequence for adding water reducers is after the flocculants and solidifiers, markedly improving the fluidity of the solidified soil, with a 0.2% dosage proving most effective. The comprehensive application of flocculation, filtration, and solidification processes successfully produces self-compacting flowable solidified soil with a lower porosity.