The invention discloses a temporary river-crossing bridge structure for water-power engineering construction and a construction method for the bridge structure. A main body of the bridge structure is formed by assembling more than two hollow arch culverts (4) on a river bed (7) in sequence, and a pavement (2) is arranged on the hollow arch culverts (4); a bridge opening for communicating the upstream with the downstream of a bridge and enabling running water to pass through is formed in each independent hollow arch culvert (4); rock block backfilling layers (8) for leveling the hollow arch culverts (4) are arranged between the hollow arch culverts (4) and the river bed (7). According to the temporary river-crossing bridge, constructors and machinery as well as equipment can safely pass through the river which is 1-2 m deep and is lower in flowing speed; meanwhile, overflowing of the river is not affected; the river-crossing bridge structure can adapt to various river sections, and is convenient and quick for construction and small in investment; after the use, the river-crossing bridge structure is easy to dismount, can be repeatedly used, and deserves to be popularized.