The causes of frequently occurred lightning accidents in the Chengnan Middle School of Dazu County, Chongqing after a mobile communication base station was constructed are analyzed by means of the monitoring data of the ADTD lightning location system in Chongqing from 2006 to 2009 The results show that the construction of the mobile communication iron tower increased the lightning strike probability of the Chengnan Middle School and the influence of lightning electromagnetic impulses, which is the major cause of the frequently occurred lightning accidents. The teaching building frequently stroke is out of the protective range of the iron tower, located in the lightning scattered strike zone of the iron tower, and does not have lightning protection devices.