Abstract: To solve the problem of feeder condition evaluation caused by the fluctuating peak loads, this paper introduces the concepts of load return level and load return period based on the generalized extreme value (GEV) distribution theory and establishes a probabilistic index T-year feeder burden rate to evaluate the burden state of distribution network. Considering the differences of load structures and grid structures of different distribution network systems, a calculation method of T-year feeder burden rate for distribution network with various types of loads by introducing the load coincidence factor because of load diversity. The distribution networks under three typical scenarios of a rural area in Anhui province, a city in Zhejiang province, and an industrial park in Jiangsu province are used as examples to analyze the feeder extreme burden rate under different return periods of "once a year", "once in five years" and "once in ten years". Meanwhile, the minimum return periods of the events with heavy loads and extra loads when the feeder extreme burden rate reaches different return levels are studied. The results and analysis of the case show that the index effectively evaluates the burden state of feeders with a low sample size, and the proposed calculation method has a wide applicability in distribution networks with various of fluctuating loads.