With the increasing of the wind turbine capacity, the busbar trunk power transmission system has become the dominant technique for wind power transmission. The tower tube of the wind power vibrates due to withstanding the influence of various wind conditions for a long time, which causes its internal busbar trunk connections fixed bolt loose and friction between conductive rows, leads to the contact resistance of the connection increases and heating continues to increase, further damages busbar trunk insulation, and even causes short circuit fault. According to this problem and based on the infrared temperature measurement technology, this paper proposes an on-line monitoring method for the first time to the heating failure of wind power busbar trunk. Meanwhile, taken into account the special busbar trunk environment, a special infrared temperature sensor is designed, and then the least square algorithm is used to calibrate the temperature, and the sensor accuracy is improved combined with temperature compensation. In order to ensure the stability of the data communication, the system uses the RS-485 network and the ZigBee wireless MESH network. In the field test, the system can realize the real-time monitoring, positioning and early warning of the heating failure of the busbar trunk. This work is supported by National Natural Science Foundation of China (No. 51177115) and Key Technology Innovation Team Project of Shaanxi Province (No. 2014KCT-16).