The existence of breeze vibration is a serious threat to the normal operation of transmission lines. In view of this, the monitoring equipment of transmission line breeze vibration monitoring system should have the characteristics of strong antimagnetic ability, high accuracy and easy installation. An online monitoring scheme of transmission line breeze vibration based on thermal imaging camera and image processing technology is designed. The implementation of the scheme in hardware and software is described in detail. The design can accurately measure the dynamic bending strain of transmission lines in real-time and online, and has the ability to resist electromagnetic interference, which effectively ensures the monitoring demand of the transmission line breeze vibration.