As a novel subgrade material utilized in the reconstruction segment of expressways, lightweight foamed soil possesses inherent characteristics of low weight and high strength. This study aims to investigate the properties and feasibility of utilizing lightweight foam soil for backfill construction in the transition section of soft soil embankments, drawing on the specific bridge head subgrade project of Guangfo-zhao Expressway, this paper elucidates the construction process and technical focal points of lightweight foam soil backfill construction, while also integrating application instances and numerical simulation methods, the impact of using lightweight foam soil as backfill material on settlement and structural deformation during both construction and operational phases in the transition section is analyzed. The findings indicate that subgrade settlement and structural deformation tendencies are significantly reduced when employing light foamed soil fill compared to conventional backfill methods, the substantial social and economic benefits derived from substituting traditional soft foundation treatments with lightweight foam soil underscore its potential as a scientifically grounded alternative for platform backfill applications.