In order to know the influence of film open ratio on the transpiration rate of maize,and the relation between water consume of maize transpiration and climate factors so as to provide theory basis for agricultural irrigation and film cultivation technique,the paper used stem flow gauge which is based on heat balance method to continually measure the transpiration rate of maize under different conditions of film open ratio,and analyzed the data of transpiration and climate. Results showed that the maize transpiration respectively presents single peak curve and multi peak curve in sunny days and cloudy days.The transpiration rate of maize decreases with the increase open ratio. The more the open ratio,the longer of time the transpiration stay at peak value.There is an exponential relationship between transpiration efficiency and filmopen ratio.Themain climate factors which affect the transpiration rate of maize are in turn solar radiation >temperature>relative humidity. The film can change the micrometeorology of maize root area to affect its transpiration rate through change air temperature and relative humidity in scope of film.