To fabricate the 5182 aluminum-polymer sandwich panels, the strength of 5182 aluminum panels, which are the skin sheets that constitutes the sandwich composite panels, is changed according to the degree of heat treatment after rolling, and the characteristics of sandwich panel are also changed. In addition, in the stress-strain curves of the sandwich panel, the serration behavior observed in the 5182 aluminum alloy sheet is also observed. This serration behavior causes surface roughness during sheet forming, which is a serious problem in application to automotive body sheet. In this study, the tensile properties of the 5182 aluminum sandwich panels at room and elevated temperature were carefully investigated by tensile test. It can be found that when the aluminum surface sheets having insufficient heat treatment time is applied, the serration behavior does not completely disappear from the temperature of the room temperature to 160℃.