In view of the challenges of the Hengsha Avenue extension project,including its extensive dike length,low crest elevation,severe wind and wave conditions,poor foundation soils,and high construction risks,the dike design in the open sea area of the Yangtze Estuary on soft foundations is investigated.Utilizing a multi-faceted research approach involving standard formula calculations,numerical modeling,and physical model verification,the design encompasses dike crest structure,armor layer,toe protection,and foundation treatment.Innovative structures and design methods are proposed,including a crest structure combining L-shaped retaining walls on both sides with rockfill core and rock-filled concrete pavement,a double-layer acropode armor system,a multi-method approach to determine toe protection dimensions,and segment-specific foundation treatment strategies on the basis of soil classification.Furthermore,considering the harsh on-site construction conditions,a series of construction-phase safety measures are implemented,such as safety platforms,auxiliary platforms,and temporary rockfill dams,summarizing key technical points for soft foundation dike design in the exposed waters of the Yangtze Estuary.The engineering structures successfully withstands two consecutive typhoons in 2024,achieving the desired project outcomes.