In order to solve the problem of bridgehead jumping caused by uneven settlement of soft soil subgrade, this paper proposes a non-excavation treatment scheme of inclined jet grouting pile reinforcement based on the demonstration project of eightword section of Xiaojiang Interchange Bridge in G15 Shenhai Expressway, the settlement amount of the eight-character bridge demonstration project and the reinforcement effect of using inclined rotary jet grouting pile to strengthen soft soil subgrade are analyzed and studied based on the FLAC3D three-dimensional numerical simulation. The results show that: The primary settlement is mainly concentrated in the period from 2000 to 2019,and the main consolidation settlement is dominant, the secondary consolidation settlement in the later period has a trend of gradual regional stability; The composite foundation composed of inclined jet grouting pile and silt soil can effectively enhance the anti-deformation ability of the soil under the embankment, and the settlement of the treated area is effectively controlled; The direction of the inclined jet grouting pile along the road length gradually decreases, and the road surface settlement also presents a gentle gradual effect through the zoning and gradual treatment of the soft soil subgrade in the jump-off section at the bridge head. The research results can provide a design basis for the treatment of soft soil subgrade in the demonstration section and have certain theoretical and practical significance.