This paper investigates the thermal performance of glass window composed of glass, silica aerogel and phase change material (PCM), which concurrently provides storage and restitution of heat, super thermal insulation and daylighting to the interior environment. To assess the glass window thermal behavior, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers was established and verified. Then, the influence of factors such as thermal conductivity, density, specific heat and thickness of silica aerogel on the thermal performance of the glass window was analyzed. The results show that the most significant controlling parameters are the thermal conductivity and thickness of silica aerogel, while the impact of density and specific heat of silica aerogel on the thermal performance of glazing unit is marginal. A proper thickness of aerogel that maximizes the exploitation of latent heat of PCM should be identified, which is between20 and 30 mm for the studied climatic conditions. It was concluded that integrating silica aerogel insulation into PCM-glass window system is an effective technology in cold regions, solving the problem that PCM cannot effectively exploit latent heat, while retaining the advantages of PCM in winter.