Abstract: Due to the randomness of wind power output, line power loss calculation of wind farm is different from that of traditional thermal power plant. Accurate calculation of line power loss determines the selection of economical conductor section, and inappropriate section of conductor will make wind farm face huge economic losses. A line power loss calculation method considering line power fluctuation was proposed, which could guide wind farm to select economical conductor section. Using the two-parameter Weibull distribution to analyze historical wind speed data, combined with wind turbine output curve, wind turbine output probability distribution model considering the randomness of wind speed was established, and line power loss of unbuilt wind farm was obtained. Economical conductor section was selected for wind farm with the minimum total cost in the whole life cycle of conductor as the principle. Based on simulation results of actual wind farm line parameters and output data, the proposed method could accurately calculate line power loss and provide basis and reference for economical conductor section selection of wind farm.