AbstractTemporary supports, as mechanical devices that bear reaction forces transmitted from jacks, play an important role in bearing replacement. Compared with medium- and small-span highway bridges, temporary support for bearing replacement in large-tonnage high-speed railway (HSR) bridges always has higher performance requirements, due to the higher stability requirements for the operation of trains, larger jacking reaction forces, and long construction period. Research and development efforts for temporary supports for bearing replacement in large-tonnage HSR bridges are imminent. In this paper, a modular temporary support with a continuous height adjustment (20 mm) is initially designed based on the principle of self-locking, followed by the investigation of the bearing capacity and stability of the designed temporary support through laboratory experiments. Finally, a case of bearing replacement of a three-span continuous box girder bridge under operating HSRs using the designed temporary support is implemented. The experiments and application suggest that the bearing capacity of the designed temporary support can reach 30,000 kN, and it has the advantages of high efficiency, labor savings, and stable bearing performance, enabling it to be popularized and applied in similar projects.