Silver-montmorillonite (Ag-MT) was effectively synthesized by microwave-assisted synthesis method in the absence of any reducing agent. Waterborne polyurethane/silver-montmorillonite (WPU/Ag-MT) antibacterial nanocomposites were then prepared by incorporating Ag-MT into WPU. The morphology, thermal properties, mechanical properties and antibacterial activity of WPU/Ag-MT nanocomposites films were characterized by SEM, TEM, EDS, TGA, tensile test and inhibition zone test. The results show that the microwave irradiation-assisted synthesis process successfully yields MT surface with small-sized and uniform distribution of sliver nanoparticles. The thermal stability and mechanical properties of waterborne polyurethane are effectively improved by incorporating Ag-MT. The maximum mass loss temperature of the hard segment increases by 11 ℃. The tensile strength and elongation at break increase by 32% and 13% respectively. The antibacterial test indicates that the WPU/Ag-MT nanocomposites exhibit excellent antibacterialactivity against E. coli and S. aureus. The results therefore reveal that WPU/Ag-MMT nanocomposite is a promising antibacterial material that can be used for antibacterial field.