The invention discloses a predicting method for a development trend of wildfire at the periphery of a power transmission line corridor. The method comprises the following steps: firstly, laying and installing a small-sized radar and a micro meteorological sensor by combining with the conditions of the power transmission line corridor; secondly, querying geographic and geomorphic data of the power transmission line corridor at the periphery of wildfire from a GIS (Geographic Information System) information platform; thirdly, setting a time interval delta t, extracting meteorological data by taking the time interval as a unit in real time, transmitting back and then caching into a database; fourthly, analyzing small-sized radar scanning data, and monitoring fire behavior in real time by using the small-sized radar; fifthly, predicting the trend of the wildfire at the periphery of the corridor by combining with a wildfire development trend simulation algorithm; sixthly, performing aid decision making on the development trend of the wildfire at a next stage by using wide-area meteorological monitoring data of the small-sized radar. According to the predicting method disclosed by the invention, refined fire behavior information of the periphery of the line corridor and medium-long term weather conditions are provided by the small-sized radar; meanwhile, the predicting method has the advantages of wide monitoring range, high meteorological data accuracy and the like.