Based on the features of lightning, design drawings, and site survey data, the risk assessment is conducted for the case of a buildingcomplex according to the theories and methods of the Risk Management of Lightning Protection IEC623052. It is concluded that the major lightening hazards of a buildingcomplex are casualties and property losses. To improve the accuracy of the risk assessment, the methods of average number and area weighting factor are adopted to determine the values of some characteristic factors and parameters. By analysis and calculation, the results indicate that under the condition of direct lightning flashes and good protection measures of earthing and potential equalization, the major lightning hazard is property loss because of the high values of risk components of the inner system malfunction caused by the lightning strikes on the lightning electric pulse. Reasonable allocation, shielding and wiring of surge protectors are suggested to reduce lightning hazards of building complexes.