The invention discloses a transmission line sag-considered current magnetic field conductor parameter inversion method. A line inversion model part, a line segmented linear inversion part and a transmission conductor position and sag estimation part are included. The method disclosed in the invention has the beneficial effects of getting rid of human control, reducing cost and improving the efficiency and the detection precision. As sag exists in the transmission line due to self gravity, line sag factors are considered in the inversion method, a conductor parameter inversion method by using aparabolic model to fit the transmission line sag is proposed, the inversion precision is improved, and the flight safety of an unmanned aerial vehicle is ensured.