There are severe ice shedding vibration problems in the 500 kV AC transmission line located in Northeast Yunnan, which is in the high altitude, heavy ice conditions. In this paper, a finite element model considering the coupling effect of transmission tower line system is established, and the vibration analysis of the system is carried out by using the modified density method. The results show that the maximum tension and displacement of vibration of the tower line system is smaller than that of the line. The tower will transfer a part of the energy to the conductor and ground wire without the ice shedding. According to the characteristics of vibration mode, the semi-span ice shedding may effectively increase the vibration displacement of the conductor to some extent, but has little effect on the tension of the conductor.