The antenna recovery swing beyond the standards is a serious failure of the radar antenna control system, which can reduce the control accuracy of the radar antenna and wear the mechanical structure of the antenna servo system. The antenna recovery swing failure of the CTL713C weather radar at Heze during the 11th Chinese National Games is analyzed. According to the angle signal flow, the antenna control circuit of the 713 radar is analyzed. Through comparing the realtime data with the normal data of the key nodes to find the fault location, the antenna recovery swing was adjusted to meet the radar requirement. It proved that the signal flow analysis is useful in the troubleshooting of radar.