In the context of the construction of new power systems, the thermal stability limit capacity of overhead distribution lines, especially the transmission capacity of interconnected lines in N-1 mode, has become a bottleneck that restricts the flexible operation and reliable power supply of the power grid. Dynamic capacity expansion technology provides an important technical means to improve the transmission capacity and asset utilization rate of existing lines, and solve peak load electricity consumption. Data monitoring is the foundation for achieving dynamic capacity expansion of overhead distribution lines. For this purpose, this article develops a wireless sensor based dynamic capacity augmentation system for overhead distribution lines. By collecting data information such as wire temperature and micro meteorology, the real-time calculation of wire current carrying capacity and invisible current carrying margin is achieved. And the device was tested and applied on a 10kV overhead line in Henan Power Grid. The results indicate that the dynamic capacity increase system for overhead distribution lines developed in this article can accurately calculate the real-time current carrying capacity of conductors, fully tap into the hidden current carrying margin, provide safe transmission capacity limits for conductors, and provide important scientific data reference for peak power transmission on the line.