An analysis is made of the uniqueness and limitation of the collection area calculation formula in the evaluation of lightning disaster risk. The common complex shaped structures are divided into three categories: rectangular building with a high point, podium building, and L shaped building, and the corresponding models are formed. According to the Technical Codes for Protection of Building Electronic Information System against Lighting (GB50343-2012), an appropriate model of collection area is devised by using the Auto CAD software. The corresponding model formula is generalized. Comparing to the empirical method, the results of the calculation method is close to true values, which provides scientific references for the evaluation of lightning disaster risk.