In order to study the cement-industrial waste-based synergistic curing of silt soil, orthogonal design tests were used to prepare a new curing agent using cement, fly ash, blast furnace slag, and phosphogypsum as curing materials. In order to evaluate the cement-industrial waste-cured soils, unconfined compressive strength tests, fluidity tests, wet and dry cycle tests, and electron microscope scanning tests were carried out. The mechanical properties and microstructure of the cement-industrial slag were revealed and used to analyze the curing mechanism. The results showed that, among the cement-industrial wastes, cement and blast furnace slag had a significant effect on the unconfined compressive strength of the specimens, and the optimal ratio for early strength was cement-fly ash-slag-phosphogypsum = 1:0.11:0.44:0.06; the optimal ratio for late strength was cement-fly ash-slag-phosphogypsum = 1:0.44:0.44:0.06. In the case of a 140% water content, the 28d compressive strengths of curing agent Ratios I and II were 550.3 kPa and 586.5 kPa, respectively. When a polycarboxylic acid water-reducing agent was mixed at 6.4%, the mobilities of curing agent Ratios I and II increased by 32.1% and 35.8%, and the 28d compressive strengths were 504.1 kPa and 548.8 kPa, respectively. When calcium chloride was incorporated at 1.5%, the early strength of the cured soil increased by 33% and 29.1% compared to that of the unadulterated case year on year, and the mobility was almost unchanged. From microanalysis, it was found that the cement-industrial waste produced the expansion hydration products calcium alumina (AFt) and calcium silicate (C-S-H) during the hydration process. The results of this study provide a certain basis and reference value for the use of marine soft soil as a fluid filling material.