To ensure the safety of train operation during the construction process of repairing ballastless tracks on high-speed railways, a temporary support system is designed. The temporary support system consists of WJ-7 type fastener system, steel pad support layer, filling and leveling layer, and anchoring system. By using numerical simulation force analysis and top push test, the structural stability of the support system is calculated, analyzed, and simulated. The research results show that the deformation of the support system under 51 kN lateral top push is less than 2 mm. In the deformation control project of ballastless track, the support system is applied to replace the existing rail sleepers for bearing. The monitoring results show that the support system can effectively maintain the geometric stability of the track during the construction process.