Abstract: Semi closed greenhouse is a new greenhouse in recent years．Greenhouse climate corridor and positive pressure air supply system are the key system design of semi closed greenhouse．Temperature distribution uniformity and wind speed of air duct in semi closed greenhouse in summer were tested to verify greenhouse cooling capacity and performance of air supply system．Test results showed that, domestic fan SFG5-4 was equipped with 35 m long air duct, air supply was relatively uniform, and wind speed was from 4.3 m/s to 4.7 m/s; for temperature distribution rule, in the same horizontal direction, average temperature difference of each point in semi closed greenhouse was within range of 1.0 °C to1.8 °C, and in the same height direction, average temperature difference of each point in greenhouse was within range of 2.2 °C to 3.5 °C, and 3.5 m wet curtain was better than 2.0 m wet curtain in cooling effect．