Abstract: Amodel for a prestressed concrete cable-stayed bridge with aΠcross-section main girder was established in a scale of one to five for a concrete cable-stayed bridge over the Jinsha River in Yibin City. The shear lag effect of this bridgewas analyzed experimentally andwas comparedwith the one obtainedwith the finite element method. The comparison shows the reliability of the experiment. The experimental result shows that for a cable-stayed bridge with aΠcross-section main girder, shear lag factor is greater at the fixed ends of its cantilevers than at its mid-span.