The invention discloses a corrugated steel plate built-in seamless expansion device between a girder and a bridge abutment and a construction method of the seamless expansion device. The expansion device comprises prefabricated steel plate elements distributed on a bridge abutment expansion joint and expansion joint filler packing layer filled above the prefabricated steel plate elements; the prefabricated steel plate elements comprise straight steel plates, corrugated steel plates and a plurality of arched reinforcing steel bars; a plurality of shear pins are fixed on the corrugated steel plates; a sliding layer is paved on the girder exposed section; the construction method of the to-be-repaired expansion device comprises the following steps: cleaning the original bridge expansion device, constructing preserved mounting grooves, constructing the girder sliding layer, assembling the prefabricated steel plate elements in the field, and mounting and constructing the expansion joint filler packing layer; the construction method of the to-be-constructed expansion device comprises the following steps: prefabricating and processing the prefabricated steel plate elements, assembling the prefabricated steel plate elements in the field, constructing the girder sliding layer, mounting the prefabricated steel plate elements, and constructing the bridge deck pavement structure and the expansion joint filler packing layer. The corrugated steel plate built-in seamless expansion device disclosed by the invention is reasonable in design, convenient to construct, and good in use effect, and can solve a plurality of problems in the existing expansion device.