Abstract: The new prefabricated light-gauge steel-concrete composite external wall panel is a new structural thermal-insulated external wall system, with light-gauge steel keel frame as its framework and the external boards of high performance concrete boards connected with the steel keel frame with studs. Thermal-insulated materials and cement fiberboards as internal boards were filled in. The wall panel could be prefabricated in plants and installed in project sites, and played the role of enclosure walls for buildings. Compared the results of the four-point bending tests and finite element simulations, the influence laws of different structural types on flexural performances of wall panels were obtained. Results showed that the wall panels had good overall mechanical properties; the light-gauge steel keel frame could significantly improve the stiffness of the composite wall panels. Besides, the simulation results by FEM showed that the thickness of concrete boards could slightly improve the overall mechanical properties of wall panels, and the thickness of thermal-insulated layer in wall panels had great influence on the bearing capacity of wall panels.