In Korea, 99.2% of protected agriculture facilities are pipe framed vinyl houses, and most of them are structurally vulnerable single span glass greenhouses. Thus, this study purposed to examine the distribution of peak external pressure coefficient in the roof surface of single span vinyl houses as well as of a set of three single span green houses. In addition, we attempted to identify factors determining the distribution shape of peak external pressure coefficient in a set of green houses using the shape of airflow analyzed through CFD software. According to the results of experiment, the peak external pressure coefficient was higher when three single span green houses were installed adjacently than when they were installed separately. As to the distribution of peak external pressure coefficient, the maximum static pressure was observed on the side walls and on the entrance and the maximum negative pressure was observed at the center of the roof surface. When the distribution of wind pressure coefficient according to wind direction was compared with the result of CFD analysis, the distribution of wind speed in the result of CFD analysis was correlated with the distribution of wind pressure coefficient.