After flocculation conditioning and chemical solidification, the engineering characteristics of high-water-content mud can be improved. If waste mud is to be recycled into embankment filler, it is bound to have certain requirements on the strength of the treated mud. In recent years, the authors have explored and proved that the vacuum preloading-flocculation-solidification combined method (VP-FSCM) can effectively treat mud slurry with high water content (>300%), and the strength of the treated mud can meet the demand for embankment filler utilization. This study has carried out a series of laboratory model tests to explore the feasibility and high efficiency of VP-FSCM process for treating waste mud (water content is about 150%-300%); and to optimize the formulation (type, dosage, etc.) of VP-FSCM process in waste mud treatment. The test results show that: (1) The undrained shear strength of the waste mud treated by VP-FSCM after 28 days is 2.76 times that of the waste mud treated by the flocculation-solidification combined method (FSCM), which proves the high efficiency and feasibility of VP-FSCM. (2) The results of dehydration / settlement characteristics and mechanical characteristics show that the optimal additives for treating waste mud by VP-FSCM process are cement (OPC), ground granulated blastfurnace slag (GGBS), quicklime (CaO) and polyacrylamide (PAM), and their optimal contents are 5%, 5%, 1.5% and 0.12% respectively. (3) Under the optimal additive type and dosage, higher vacuum pressure results in greater undrained shear strength of the treated waste mud and lower moisture content after curing.