Abstract: Lamps of cable-stayed bridges are installed on the cables, which might be unstable subjected to wind load. Corresponding to the preliminary installation plan of lamps of a bridge in South China, Specimen of stay cables with lamps were made with the scale of 1∶1. Wind tunnel tests for both aerodynamic forces and for galloping were carried out. Results show that the existing of two parallel steel wires in the preliminary installation plan will cause the occurring of galloping. Knowing that, a modified plan is proposed, which throws away the two parallel steel wires. The stability of the proposed installation plan is verified by detailed wind tunnel tests.