To reveal the long-term deformation characteristics and the influence of soil parameters of solidified shield muck used for high-fill subgrade, this article establishes the numerical model based on FLAC, investigating the period of construction and long-term deformation characteristics and the influence of soil parameters on the muck after solidification when used as subgrade fill. The study found that, upon completion of the subgrade construction, the vertical displacements at the middle positions of the bottom and top of the subgrade reach 95.7 mm and 168.7 mm, respectively, while the horizontal displacements at the ends of the bottom and top of the subgrade are 17.4 mm and 4.5 mm, respectively. After 20 years of construction, the vertical displacements at the midpoint of the subgrade's bottom and top have increased to 108.9 mm and 180.7 mm, respectively, while the horizontal displacements at both ends of the bottom and top are 28.9 mm and 19.0 mm, respectively. The subgrade slope angle and the particle size of the solidified soil have the significant impact on the horizontal displacement of the subgrade, but show no notable effect on the vertical displacements; the elastic modulus of both the subgrade fill and foundation soil significantly influences the overall vertical and horizontal displacements of the subgrade soil.