A metallic nanomesh composite filter is an optical transparent filter coating based on alternating dielectric layers and metallic nanomeshes, which has very high transparency in the visible range and very high reflectance in the near-infrared and infrared range. This invention greatly improves the heat shielding properties of windows and glasses that reduce the heat into buildings in the summertime and also prevent heat getting out of the buildings in the winter, which will significantly improve the building energy efficiency.