The development of a green and environmentally friendly window system is always the upmost target among other requirements for modern buildings. Here, a smart window with a dynamic regulation mode was fabricated by integrating a functional layer of natural polymer thermoresponse starch (TRS) and a joule heating film (JHF) of highly transparent silver nanowires (AgNWs)/cellulose. With cellulose, the mismatch of refractive index between air and AgNWs was significantly overcame, resulting in a JHF with high visible transmittance. The excellent joule heating performance of the JHF endowed the smart window system with a dynamic regulation mode driven by a low input of voltage (5.0 V) and increased energy efficiency. This smart window displayed excellent solar modulation property of 17.9% with high average luminous transmittance of 57.8%, representing a remarkable type of smart window.