Abstract: The electric-geometric model was used to calculate the position factor （C_D） value in the risk assessment of lightning strikes. Combined with the distribution of the lightning current amplitude probabilities in Hubei province, the value of the position factor and the equivalent area of the evaluation object were analyzed and calculated with actual examples. Then the evaluation object calculated by the above method was verified by AutoCAD drawing method, and it was concluded that this method was limited in the scope of application, and it could not accurately represent the impact of the surrounding building to the equivalent intercept area of the evaluation object.

Key words: electro-geometric model, position factor, equivalent area