Abstract: Considering that the safety coefficient is low when a shallow-buried long-span highway tunnel passes under an existing railway station (or within a short distance), the section of the Dongfu tunnel that passes under the existing Xiamen-Shenzhen railway station is taken as a project example in this paper. Through a theoretical analysis and technical comparison, an overall scheme of construction techniques is determined that is the combination of the following: reinforcing the tunnel's surrounding rock and soil mass in the excavation direction using the pipe-roofing method, setting the pile cap as provisional pier on the digging pile, structural selection and security checks for the digging pile, jacking up the existing railway track by erection of a 24m D-shaped beam, reinforcing the steel rail with a longitudinal and transverse lintel, reserving core soil in an arc-shaped heading, monitoring settlement, and analyzing the reinforcement effect. The results show that the reinforcement effect is remarkable, and can rapidly and effectively restrict stratum settling in the under-passing section; the pipe on the arc plays a load-bearing role while the D-shaped beam reduces the external load on the pipe-roofing system; thus, the safety coefficient of the under-passing tunnel and the existing railway operation is highly improved, and the expected effect is achieved.