Abstract: According to some 220 kV transmission line malfunction leading to the related generatior unit trip, and leading to other generator unit with the same bus turbine vibration rush but keep the network running in the mean time. The accident is introduced in detail,and is analyzed the reasons from many angles and put forward the solution. It can play a reference role for avoiding similar accidents in power grid operation, and also prompt power generation enterprises to check hidden dangers in advance and take countermeasures.