Abstract: Stiffness composite pipe piles have significant advantages in the excavation and support structure of highway reconstruction and expansion subgrade. However, stiffness composite pipe piles are often used in engineering to bear vertical loads in foundation engineering, and there is relatively little research on bearing horizontal loads. To study the bearing characteristics of stiffness composite pipe piles as support structures, a combination of field experiments and numerical simulations was used to analyze the stress and deformation of stiffness composite pipe pile support structures during embankment excavation. On site testing showed that the maximum horizontal displacement of the stiffness composite pipe pile after excavation of 4.2 m is 8.14 mm, and the maximum bending moment of the core pile is 63.15 kN·m. The results show that the stiffness composite pipe pile has good deformation control capacity and bearing characteristics, which can meet the deformation control requirements of the supporting structure, and the deformation mode conforms to the deformation characteristics of the cantilever supporting structure. The bending moment distribution ratio between the core pile and the outer wrapping layer is positively correlated with its stiffness ratio. The supporting performance of three different pile types is compared and analyzed. Under the condition of the same size, the supporting efficiency of the mortar stiff composite pipe pile is basically equivalent to that of the concrete cast-in-place pile with the same diameter, which is about 30% higher than that of the cement soil stiff composite pipe pile.