Abstract: In reclamation projects for port construction, the pre-reinforcement of flow plastic fill soils is critical for promoting deep drainage consolidation and enhancing subgrade bearing capacity. To address the limitations of high-cost and low-efficiency in conventional earth fill methods, this study proposes a “steel frame-geotextile system” pre-reinforcement technology, distinguished by its high efficiency, cost-effectiveness, and material recyclability. This paper explored the mechanical mechanism of the proposed technology, introducing key physical-mechanical parameters to refine the bearing capacity formula. It elucidated the sensitivity relationship between the pre-reinforcement ultimate bearing capacity and geosynthetic parameters, and explored the scientific validity of this pre-reinforcement method. The results demonstrate that the dual foundation structure with a high modulus ratio effectively distributes the overburden load, reducing the additional stress in flowable fill soils. Geotextile, under loading, deforms and generates frictional resistance and anchoring effect, enhancing the load-bearing capacity of flow plastic soils. The pre-reinforcement effectiveness is linearly proportional to the geotextile's equivalent tensile strength and exponentially inversely related to the ultimate strain, with the former exerting a more significant influence. In engineering practice, materials with slightly higher tensile strength should be selected to withstand construction disturbances and prevent pre-reinforcement failure. In the context of the engineering example provided in this study, it is shown that if the conventional earth fill method was used to achieve the same reinforcement efficacy, the required earth fill layer thickness would need to be at least 9.13 m. This highlights the superior efficiency and vast potential for wider application of the proposed method. This study offers both a practical scheme and theoretical guidance for pre-reinforcement in the construction of flow plastic soils for drainage plates.