Abstract:According to the total lightning data of China's provinces among the lightning data obtained from U.S. satellite observations, we calculate the average ground lightning density. Simultaneously according to the annual average data of thunderstorm days in 220 spots around various provincial areas, the average ground lightning density of the provinces are calculated by the formula in 《Design code for protection of structures against lightning》(2000 version). Comparing the results of the two kinds of methods, it found that there were great differences, and the differences of some areas were significant. Putting forward the concept of the ground lightning density of thunderstorm day unit, analysing the difference between provinces all over the country and its reason, pointing out it could roughly reflect the distribution of the density of ground lightning adaptable to the characteristics of the Chinas climate, further analysing the lightning data of the artificial observation and lightning locator of Huzhou in 2007, we obtain the same conclusion. Thus the density of ground lightning calculated by the formula in 《Design code for protection of structures against lightning》(2000 version) should be further amended and improved.