With the sound of energy saving horn, smart windows with dynamic adjustment of light transmittance are particularly important in today’s high-energy buildings. Due to the excellent external field response performance and good processing performance, liquid crystal/polymer composite systems exhibit various application prospects in smart window that dynamically modulates light transmittance. According to the regulation mechanism, smart windows fabricated by liquid crystal/polymer composite can be divided into electrochromic, thermoschromic, mechanochromic and photochromic. Among them, electrochromic and thermochromic windows are of great importance because of the feasibility of preparation and application. In recent years, the emerging technologies that combined smart window technology with solar cells, are expected to promote the green and intelligent innovation in the field of architecture. In this paper, five types of liquid crystal/polymer composite for smart window application were introduced, that is, polymer dispersed liquid crystal, polymer stabilized liquid crystal, a coexistent system of polymer dispersed and stabilized liquid crystal, polymer network liquid crystal, and polymer wall stabilized liquid crystal. Their microstructures and response mechanisms were summarized. The research progress and combined applications with other emerging technologies were reviewed. Finally, the future development trend of smart windows is briefly prospected.