On June 23,2011,five sites including Xiqing Gate and the Arrow Station in the Palace Museum were struck by lightning.The weather condition and the characteristics of atmospheric electric field and lightning distribution during the lightning stroke period are analyzed in detail utilizing the routine weather data,satellite data,radar echo data,the atmospheric electric field data as well as the lightning data.Then,on the basis of the field investigation of lightning stroke in each place,the specific causes of lightning stroke and the weak link of lightning protection are analyzed.Aiming at these existent problems,the improvement suggestions are given.Especially,the small scale lightning monitoring and early warning measures are put forward.Thus the precise monitoring and warning measures will be implemented and the lightning protection of the Palace Museum will be improved.Some references are provided for lightning monitoring & warning and the selection of lightning protection measures in the cultural relics sites.