The fracture reason analysis of oscillator wire was performed of vertical log-periodic antenna,which mounted somewhere in the north of China in 2018. Through the analysis of two possibilities of brass material fracture,the results show the reason of brass oscillator wire fracture is fatigue damage. The main causes of fatigue damage are the tension adjustment of the antenna cable and the large local temperature difference,which results in the stress of the oscillator wire far exceeding the original design stress. According to the reason breakage of the brass oscillator wire,an improved scheme is proposed to meet the antenna requirements in this area.