The filling plays a very important role in the damping performance of materials and structures. The major objective of this paper is to determine the effect of the dimensions and quantity of the glass flakes on the damping factor polyurethane materials and different damping structures, such as free damping structure and constrained damping structure, which can provide basic foundational data for the modification of damping materials and the damping structure design.The results showed glass flakes were directional arranged and formed a multilayer laminated structure in polyurethane resin. With the addition of glass flakes, the damping factor increased due to the more energy consumptionresulted from the interfacial friction between glass flakes and damping resin. But too much glass flakes led to decreasing of damping factor because of the limited interfacial friction. In addition, with the size of glass flakes increased, the damping factor of polyurethane damping structure increased, and the rate of growth decreased.