SIn order to study the reasonableness of steel-concrete composite bridges in interchange engineering, structural performance of composite two plate girders, single- trapezoidal box composite girders and narrow-box composite girders are analyzed. Based on the related engineering cases in Japan, the economic indicators of narrow-box composite girders and reinforced concrete box girder bridges are calculated in detail. The results show that narrow-box composite girders are the most suitable for interchange engineering and the most economical span layout is arranged as N×40m. Compared with continuous cast-in-place reinforced concrete girder bridges, the unit cost of continuous narrow-box composite girders bridges is expected to be saved by about 20%, and the overall performance of narrow-box composite girders is better..