The invention discloses an unmanned-aerial-vehicle-image-based geological disaster monitoring system and method for power transmission line. The system is composed of a power data interface module, a topographic data interface module, a remote sensing interface module, a track planning module, a remote sensing image interface module, a remote sensing data interface module, a data matching processing module, a data training module, a geological disaster monitoring module, and a monitoring result display module. On the basis of combination of power data, topographic data, and remote sensing parameter data with geological disaster monitoring, the timeliness of power rescue work can be improved. Meanwhile, remote sensing image data and remote sensing data are managed effectively, so that the efficiency of geological disaster monitoring can be enhanced. In addition, according to the geological disaster monitoring method, when several kinds of data are inputted, the type of the inputted data can be determined and corresponding processing is carried out based on the data type, so that the geological disaster monitoring efficiency can be improved.