Green roofs and night ventilation are well-known passive techniques for energy saving during cooling period. This study refers to the analysis of thermal properties and energy performance of the combination of green roof and night ventilation. Firstly, a field experiment was conducted to compare the thermal performance of green roof and bare roof when combining with night ventilation. Three series experiments were carried out to analyze cooling effect of green roof with and without night ventilation on summer sunny day and another experiment with natural ventilation all day long on summer rainy day was also monitored. Then, data from the field study were used to validate the green roof and night ventilation model incorporated within a building energy simulation program. This model was then used to estimate the energy saving for an office building in three typical climates. Results show that combining green roofs and night ventilation can significantly reduce the indoor air temperature and heat gains on sunny day but have no appreciable effect on rainy day. Because the cooling potential of green roof and night ventilation strongly depends on the climate and thermal mass, a simple equation to assess the air flow rate of night ventilation when combined with green roof was proposed. Furthermore, the correlation analysis between weather factors and cooling effect of green roofs as well as the air organization mode for night ventilation is also discussed. (C) 2017 Elsevier B.V. All rights reserved.