By calculating the switching overvoltage and the induced overvoltage on the 500kV double-circuit transmission lines of Xiangyun Ⅰ & Ⅱ and checking the approach distance of live working

the risk rate under minimum approach distance of live working on typical tower types was acquired.The live working methods of entering the electric field are proposed.The risk rate of entering the equal potential on the intermediate tower with suspending chair or insulating ladder under crossarm is less than 2.3×10-12.The risk rate of entering the equal potential on the angle tower along the tension insulator string is less than 5.8×10-8.The theoretical calculation and the practical operation prove that it is safe to perform live working on the transmission lines of Xiangyun Ⅰ & Ⅱ.