Abstract: Semi-closed greenhouse is a new type of greenhouse with high controllability，high uniformity，low ventilation rate，positive pressure，high efficiency and energy saving.Cooling effect of semi-closed greenhouse in summer was studied combined with example of greenhouse in Tongzhou Yujiawu area，Beijing city.Existing fans were been upgraded，and temperature，humidity，light intensity，wind speed and other test data in greenhouse were recorded.Analysis results showed that semi-closed greenhouse suited for large scale production，less fans and cooling pads were needed，compared with ordinary greenhouse，temperature in semi-closed greenhouse was more evenly，energy saving effect was more obvious and anti-insect effect was better in summer.