Based on the contrast analysis of loads provided in foreign and Chinese standards, analysis and discussion are mentioned about the definition and estimation of dynamic wind pressures for multi span greenhouse structural design in details. Meanwhile, taking advantage of past experience in greenhouse structural design a practical method which can be used in greenhouse design was given for wind load. Under the present conditions, it is unnecessary to make modification of statistical reappearing factor in calculation wind load dynamic pressure when considering the coefficients of wind pressure depending on height and the gust factor according to Chinese architectural structure load standards(GBJ9-87).