Abstract: According to the calculation method of the number of lightning per annum in buildings given in national standard GB 50057-2010 and international standard IEC 62305-2：2010, the three components of the correction/location factor, the lightning ground flash density where the building located and the equivalent area of buildings were compared and analyzed respectively. The relationship between the ratio of the annual number of lightning in two standards and the length, width and height of the building was studied under different conditions. The limitations and rationality of the calculating methods of the annual number of lightning in two standards were summarized in order to provide a basis for the design of lightning protection and lightning risk assessment.

Key words: lightning ground flash density, location factor, equivalent area