A new method was presented for power load forecasting.Based on the fuzzyclustering technique,the historical samples of power load and its relative environmental factors wereclassified into several typical categories,the fuzzy numbers and sets were then used to describe thepatterns of load variation and the features of the environmental factors for every class. Finally,byunderstanding the state of future environmental factors, the future power load can be predictedthrough determining the category of load variation pottern. The validity of the proposed method wasverified with a practical medium-term load forecasting.