Abstract: Addressing the challenges of height constraints， tight construction schedules， and significant traffic disruption encountered during the reconstruction of widely used small-to-medium span hollow slab bridges， this study proposes a rapid replacement technology for fully prefabricated steel-concrete composite girders based on epoxy mortar connections. In a 13 m span slab replacement project， the structural system adopted an “I-shaped steel girder + epoxy mortar bedding + prefabricated concrete deck panel” configuration. By replacing traditional cast-in-place concrete joints with epoxy mortar wet joints， an equal-height replacement of the original hollow slabs was achieved. The mechanical properties and construction processes of this bridge type were systematically investigated through refined finite element analysis， laboratory tests， and on-site engineering verification. The results indicated that the ultimate bearing capacity of the composite girder reached 4.8 times the service load， exhibiting a distinct ductile failure characteristic where the “steel girder yields before concrete crushing occurs”. Implementation of this technology allowed rapid installation of the superstructure within 24 hours. Although the direct material cost was approximately 20% higher than that of hollow slabs， the technology presented a significant advantage in total integrated cost due to reduced social costs from shortened construction periods and the full utilization of existing substructures. This study provides a feasible solution for the rapid renovation of small-to-medium span （10~16 m） hollow slab bridges.