Using the Delphi and other methods, the present research constructed the index system for the evaluation of the impact of mega sports events over urban development. Taking the 6^th and the 9^th National Games as examples and using the evaluation index system, the paper appraised the impact of mega sports events over the development of Guangzhou city. The macro evaluation results didn' t show obvious effect of mega events over the economic development of Guangzhou city. And the micro results indicated that the effect mainly consisted in the exp...