In order to solve the problem of the No. 13 LOC got struck by thunder in Chizhou Jiuhuashan Airport, firstly, the field signal was measured and the fault of transmitter system may clear. Secondly, the transmission characteristics of the transmission lines and cables between the antenna distribution unit and the antenna elements are checked and the results are all normal. Finally, the monitoring system and the antenna distribution unit are respectively examined and checked, which found the antenna combine board, the interface board and the four-ways power splitter are all faulty, and then the system returned to normal after the replacement of these parts.