The invention discloses a pre-bending construction method for steel-concrete combined girders, and is applied to the technical field of bridge construction. The pre-bending construction method includes S10, mounting steel girders, arranging pre-bending girders below the steel girders along the vertical direction of bridge girders, and connecting two ends of the pre-bending girders to the steel girders through pre-bending and tensioning pieces directly or indirectly; S20, arranging pre-bending supports at midspan positions of the steel girders and on the pre-bending girders; S30, pre-bending the steel girders by tensioning the pre-bending and tensioning pieces and/or lifting the pre-bending supports; S40, pouring concrete on the steel girders to form concrete bridge faceplates. The pre-bending construction method has the advantages that the pre-bending girders are arranged below the bridge girders and are connected with the steel girders through the pre-bending and tensioning pieces, the pre-bending supports are arranged between pre-bending bridge spans and the steel girders, and pre-bending force is applied to the steel girders through the pre-bending and tensioning pieces at two ends of the pre-bending girders and/or pre-stressing force application pieces on the pre-bending supports, so that erection of temporary support frames (support piles) is avoided, passing of vehicles below bridges is not affected greatly, and great convenience is brought to construction.